GTA

All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Engineering- Research & Development => Topic started by: George Schmermund on December 04, 2016, 08:53:52 PM

Title: Hacking the Crosman Vigilante
Post by: George Schmermund on December 04, 2016, 08:53:52 PM

I bought a couple of Crosman Vigilante pistols recently for doing some hacking in the shop. I'm keeping one of them unaltered as a reference gun. The other one is getting several mods that will require machining and electronics work. Today's effort was to establish a baseline for the unaltered gun.

First off, I've already dismantled the test-bed gun and started some machining projects on it. The barrel was swapped out for a 1077 barrel cut down to a 10" length. The 1077 one will make 2 long barrels to play with. I crowned the new 10" barrel and used a 60º cutter to make a new forcing cone on the breech end. The latch clip on both barrel housings is a little flaky, so I used a micro-spot welder to attach a .015" thick 'U' shaped piece of nickel plated steel to the original retainer clip. This new retainer clip fits exactly into the slot in the housing and takes out the factory-made slop. This new latch arrangement keeps the forcing cone pressed up squarely to the face of the pellet clip and eliminates barrel droop.

The frame assembly was dismantled completely for inspection. This is a very simple gun and is easy to work on. After removing the valve body and getting the valve opened up I could examine it's private parts. The valve stem looked like a good place to start tampering, though the stem is harder than the hubs of (?) and wouldn't be easy to do conventional machining on. This type of part is what I like to use the EDM for. It only took a few minutes to sink 2 new .060" ports between the existing ones. I could have gone larger in diameter, but I'm not sure of the impulse stresses that the hammer generates yet. Down the road some I'll make a fixture to hold the stem and do a drop weight test on it and see what it can take. I've ordered some extra stems from Crosman. A small force gauge can then be installed onto the valve body in place of the stem. This test will characterize the hammer's impulse energy. The springs can also be tuned using this information.

Back to today's baseline testing. One of the flies in the ointment is that CO2 as a propellant is very temperature sensitive and the whole system needs to be stabilized if good numbers are to be generated in these tests. To get useful testing results the valve stem mod needed to be tested as the single variable in the procedure. One of the nice things about the Vigilante design is that the barrel housing can be swapped out by removing just 1 screw. This allowed the unmodified barrel (well, not completely unmodified, I did close the barrel latch gap) to be used on both gun frames with a quick swap.

I'll describe my methodology in the next post after the numbers are crunched. This will be the start of many tests while the hacking progress continues.

   
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 05, 2016, 12:19:33 AM
awesome, always wanted to see one of these pushed to the limits
Title: Re: Hacking the Crosman Vigilante
Post by: AmBraCol on December 07, 2016, 10:57:28 AM
Subscribed - and hoping for pics.  :-D
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 07, 2016, 09:30:05 PM
Here are a couple of images of what's going on with the Vigilante mods. The valve stem is in the EDM and the view is of one of the new .060" ports. The other 2 views are of an original barrel being tested for warp in a 'V' block and in the lathe for a re-crowning of the muzzle and then resurfacing and polishing of the forcing cone. Not too interesting, but there was a request for some pix.

I can report that the barrel was unusually straight, but then it's only 6" long. The factory machining on both the muzzle and the forcing cone were horrible! I'm glad that I took the time to clean them up. I still have an original factory 6" barrel for baseline testing. More to come!
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 07, 2016, 09:33:15 PM
very nice tooling .. will you be going with a longer barrel>? id imagine 8 inches of turned down crosman barrel would yield 30 fps or so.. furthermore the stem is identical to my paintball gun stem with the breather holes.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 09, 2016, 03:59:50 PM
Here are a few more pix of the project. The barrel (as stated earlier) is 10" long. The barrel shroud is 1" Delrin. I plan to do some creative baffling in it.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 09, 2016, 11:18:50 PM
thsat looks incredible , sorry i missed the 10 inch part!
Title: Re: Hacking the Crosman Vigilante
Post by: UCChris on December 09, 2016, 11:25:57 PM
Looking awesome!
Title: Re: Hacking the Crosman Vigilante
Post by: TleVta on December 10, 2016, 12:36:45 AM
Impressive. You may need one of these when you're done:

http://www.airgundepot.com/a-n-t-co2-hpa-conversion-kit-bulk-co2-adapter-air-venturi-coiled-remote-co2-refilling-line.html (http://www.airgundepot.com/a-n-t-co2-hpa-conversion-kit-bulk-co2-adapter-air-venturi-coiled-remote-co2-refilling-line.html)

I just put one on a Sig X5, and I like it already.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 10, 2016, 03:16:39 PM
One of the things that interferes with getting useful numbers when testing velocity and energy to evaluate CO2 guns is the need for setting and maintaining the temperature of the gas. This problem is overcome when bench testing because the gun is usually fixed in a ridge mount and the experiment can be instrumented close by. I've developed a multi-channel arrangement that gives me a settable temperature that can be read and controlled by using a regulated power supply and micro thermal detectors attached to the gun parts that I'm interested in tracking.

The use of plastic for the barrel housing and pellet clip on the Vigilante is fortuitous. It allows thermal isolation of the barrel from the gun's metal frame. The frame grips are also plastic and give good isolation to the powerlet from ambient temperature. Using only a couple of watts of adjustable power it is easy to set up experiments where the temperature can be set and remain stable.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 11, 2016, 05:46:28 PM
Here are some pix of the powerlet heaters. They keep the powerlet and frame at a controlled temperature for ballistics testing. I'm using a lab bench power supply to control the power input to the heaters. The micro thermistors are not shown, but they can be placed anywhere on the powerlet and frame to get a temperature profile during the testing. When the testing is done the heaters can then be powered buy a tactical flashlight that can be mounted to the lower rail. the light can be reconfigured to be just a source of power using it's lithium battery. The energy storage in these batteries is substantial. By using shaped foam insulation in the grips and a very simple thermal switch the system will be quite efficient.
Title: Re: Hacking the Crosman Vigilante
Post by: AmBraCol on December 11, 2016, 10:51:38 PM
Now to find a way to make it portable... ;D
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 12, 2016, 05:24:26 PM


One of the measurements that has significant meaning when you're hacking airguns is muzzle energy. I use a Combro CB-625 Chronograph that attaches to the muzzles of the guns I want to test. It's accurate and gives useful numbers for velocity and energy. I like the small form factor of this instrument because my ballistics bench is designed to be fairly compact and efficient. I use a quiet trap that I've designed which incorporates a new type of proprietary ballistic tile. This tile is being used experimentally as an insert for fragmentary shrapnel flack vests. I don't have any PCP guns, so I use The CCI 'Quiet-22' bullets as a proxy for a PCP gun with 45 fpe. This is a 40 grain projectile and provides me with the upper edge of energy that I'm interested in evaluating on the bench. The typical distance of the gun muzzles to the trap is 1' or less. This arrangement allows me to safely capture all projectiles up to 45 fpe in the trap without concern for any rebound or over penetration.

Anyhow, back to the measurements. Muzzle energy is generally not as easy to mentally picture as is velocity. Sometimes, when the lighting is right, you can actually see a pellet or bullet in flight and get a feel for it's velocity. Muzzle energy on the other hand is difficult to reify. Dr. Beeman, in one of his classic white papers, suggested that shooting at a lineup of soda cans might be used as reasonable assessment of pellet energy. He also admitted that shooting at a series of cylinders is another set of problems. Plinking, of course, has a large component of can shooting involved with it and there are any number of pellet energy guesses arrived at using this method.

I needed something that would be suitably small for bench testing the Vigilante and other mods. It must also allow for an adjustable energy absorption rate that is reproducible and at least semi-quantitative. It must also be able to display an energy representation of the projectile in a highly visible manner that will allow 3D views. There are various ways to do this using things like gelatin, different soaps, modeling clay, etc. The method that I decided to use is a mixture of mineral oil and a polymer resin. This combination results in a rubbery gel with remarkable clarity and is very good at capturing airgun pellets. The gel can be melted in the kitchen oven and cast into various shapes. I use a mini bread loaf pan to mold the gel.

The gel itself is not very interesting to shoot at, but with a little imagination it can be vastly improved to provide a lot of energy information. Using a micrometer, the wall thickness of various cans can be measured. This is just to get an approximation of what the average can's wall thicknesses might be. I then got some aluminum flashing from the hardware store and bent pieces of it into U shapes. These stand up in the pan when the gel is melted. Each 'U' can be made from whatever material and thickness you choose.

The pix show some of the tests I've done using different pellets and BBs from different airguns. For comparison, the gel has about 80% of the density of typical small mammal flesh. The metal (or whatever you want to cast into the gel) can be used to simulate skeletal structures. I'm only concerned with yard rodents, so I consider the cast molds I make to be a reasonable synthetic rat. Yes, this all has to do with hacking the Vigilante! 
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 12, 2016, 05:31:59 PM
very cool, this is by far the most interesting thread going on at the moment..Electrically heated co2s in a decked out vigilante is on the wild side. I guess an accuracy test will be in order
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 13, 2016, 04:01:19 PM
There was a request for an accuracy test with these hacks. The photo is of a 10 shot group @ 15 feet. The pellets were 7.4 gr CP Destroyers. The average velocities were in the mid 550's fps. That's about 5 fpe. The temperature of the Powerlet and frame was set to 80º F.  I can get the energy up higher by setting the temperature higher, but I consider this to be a reasonable accuracy test for how things are set up right now.

I predict that this will be a good gun for controlling the rats that are in the ivy and trees in the backyard. Any target more than 15 or 20 feet away will get the rifle treatment. 
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 13, 2016, 04:05:02 PM
thats incredible ! I dont know how efficient the heaters are but it would be nice during the colder months if it also warmed your hands /What do you think about a dummy co2 and hpa tank? Do you feel the valve is at its full potential as is ?
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 13, 2016, 08:58:49 PM
As far as hand warmers go, I'll leave that to someone else. My plan is to arrange thermal insulation in the grips to keep as much heat inside as possible.

At the moment I have no interest in HPA. Although, up until a couple of months ago I had no interest in airguns.

The valve is doing more than it's task right now. The report is still considerably louder than I had planned on, so a lot of gas is being wasted just to make noise. I did expect to do some baffling on the barrel shroud, but not as much as it will take to quiet this gun down. I have some pressure transducers with very fast rise times that I plan to use for a gas pressure system analysis. These are the experiments that keep me interested in doing the hacks.

Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 13, 2016, 09:03:36 PM
Sounds good ( no pun) keep pluggin away!
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 18, 2016, 09:53:48 PM
I've Added a muzzle choke to the mix. The method is quite easy and is describe in the thread on choked barrels that was recently posted. It may be of interest to any of the Vigilante fans that are here.

Title: Re: Hacking the Crosman Vigilante
Post by: classicalgas on December 22, 2016, 02:59:44 AM
Looks like you are going through the same process I did back in the 80's on the same platform (crosman 357) and again around 2000. The barrel choke and clip are just the bare beginnings of what you can do to them, take a look at blueprinting the cylinders, and reaming the chambers to a smooth taper. The sights can be reshaped for  less glare and better resolution, the trigger can be honed down under a crisp pound, and a roller on the spring leg will make a huge difference in feel and consistency.

I can't post pics, but there are a bunch in the crosman forum archives, including a slab side carbon fiber 10" barrel, and one in .22

I found that running on HPA, much more than 900 psi actually reduced power..the soft seat under that big valve  doesn't like high pressures, the hammer wont lift it enough when the pressure goes up.A harder seal material might be worth a try.



Title: Re: Hacking the Crosman Vigilante
Post by: classicalgas on December 23, 2016, 04:33:02 PM
More on the Vigi/357 valve. The volume downstream of the valve seat is so large compared to the   storage volume of the valve (and the cartridge volume doesn't contribute anything during the shot, with that tiny feed tube) that trying to wring more power out of the valve is futile. Heavier or shimmed spring, heavier hammer, radiused ports in the poppet (polished out with abrasive cord) I tried them all.With a 6" barrel, no combination gave me more than 30 fps...but an 8" barrel alone is worth 40 or more fps over a 6" , a 10" is worth another 30 or so.

The big payoffs are in accuracy improvements, sights,  long barrels, and reducing leakage during the shot. Fully developed, the crosman revolvers will shoot as accurately  as any repeater up to about 4x their price.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 24, 2016, 10:08:31 PM
I finally got around to starting the tests on the new valve stem port performance. The barrel is the same 10" one from previous posts. It's now going to be dedicated to doing pressure testing on all of the Vigilante hacks. The pressure gauge is rated at 1500 PSI with a rise time of ~1 ms. That should be enough to cover most of the bases. The barrel can be adjusted to different positions in the housing by using the compression fitting at the muzzle end. This allows testing with and without the pellet clip in place.  The clip is another variable that can be further evaluated in the next testing session.

I want to wish you all an enjoyable Holiday! Also, I appreciate the positive comments about the project. 



Title: Re: Hacking the Crosman Vigilante
Post by: kj on December 25, 2016, 01:37:09 AM
intresting work on this pistol. i remember i brought up the idea of heating the co2 source about 8 years ago on a different forum. everyone said i was going to blow myself up, that was the nice stuff they said. lol . very innovative work. keep at it.

peace
kj
Title: Re: Hacking the Crosman Vigilante
Post by: TleVta on December 25, 2016, 01:39:58 AM
I have ordered one of these pistols so that I may follow this thread more closely...
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 25, 2016, 11:04:12 AM
Im not really understanding the latest innovation.. What exact purpose is the new pressure rig gonna serve?
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 25, 2016, 04:02:24 PM
The pressure transducer and barrel are a fixed volume. The powerplant on the closed side of the valve is a quasi-fixed volume with a high impedance connection to the Powerlet.  By recording the pressure/time curve starting when the hammer strikes the stem, I expect to see a lot of stuff happening between the opening and closing of the valve. Any change made to the gas system, even small ones, should be reflected in the P/T curve. The temperature will be held constant at ~80º F. This is an experiment. If I already knew what the outcome was going to be, then the test would only be a demonstration.

Also, by leaving the pellet clip out of the measurement I'll be looking at only the forcing cone against the valve outlet as a source of leakage in the gas transport system. Once the signature of the original P/T curve is generated, it can be checked for repeatability. Any modifications to the clip can then be evaluated. This will all take time to accomplish, but I find the testing to be as enjoyable as the shooting. Having a signature curve will also be used to evaluate any changes made on the powerplant side of the valve.

One test is worth at least 10 expert opinions. I hope this explains the direction that I'm heading in.



Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 25, 2016, 10:15:15 PM
Yes, it cleared things up perfectly.. Will be looking forward to the results.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 30, 2016, 09:26:42 PM
I've managed to start doing some testing on the Vigilante pressure measurements using the valve stem with the new ports. As can be seen in the photo, the time to peak is about 1.5 ms from baseline to peak. The rise time (10% to 90%) would be even shorter. This is very close to the manufacturers claim for rise time. Therefor, the measurement could easily be compromised by a slow transducer. The good part is that I now have a fair idea of what the pressure is at the end of the test barrel. This will allow the use of a much faster transducer that has a lower max pressure limit that I didn't want to use blindly.

I'll post some more pix soon that will compare the unmodified stem with the newly ported stem using the new transducer. From what I've seen so far, there will probably be a round or two of speculation as to what's going on. These pressure profiles are the sort of stuff I've been looking for. Stay tuned!


Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 31, 2016, 12:06:34 AM
Im very impressed by the data collection dlligence.
Title: Re: Hacking the Crosman Vigilante
Post by: Geoff on December 31, 2016, 07:40:27 AM
Impressive. You may need one of these when you're done:

http://www.airgundepot.com/a-n-t-co2-hpa-conversion-kit-bulk-co2-adapter-air-venturi-coiled-remote-co2-refilling-line.html (http://www.airgundepot.com/a-n-t-co2-hpa-conversion-kit-bulk-co2-adapter-air-venturi-coiled-remote-co2-refilling-line.html)

I just put one on a Sig X5, and I like it already.

thanks for the link.  bookmarked it in case I want to get more shots
Title: Re: Hacking the Crosman Vigilante
Post by: ray1377 on December 31, 2016, 04:20:32 PM
Wow, following closely!
Ray
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 31, 2016, 09:37:01 PM
I thought that it might be of interest to see how the pressure measurements are evolving. The Setra device was a good start as far as getting an idea about the magnitude of the peak pressure, but I didn't expect to see such fast rise times from the power plant. The new transducer is an Endevco 8510C type and it's pressure range is safely within the known pressures for now.

As the photos show, there is considerable difference in the size of the two instruments. The Endevco has a resonance frequency of 500,000 Hz. The general rule of thump is that you try to keep your measurements in the realm of 1/3 of a transducers natural frequency. Obviously the rise times of the testing that I'm dealing with now will never come close to this new transducer's frequency boundary. This will eliminate phase shifting and other non-linearity.

I've added another 90º elbow to increase the volume at the business end of the measurement and to decrease the likelihood of anything getting blown straight into the transducer. I don't want to blow a hole through the instrument's  diaphragm. So far the measurements are aimed at the relative differences of the two valve stems. The absolute values of the data are not of any importance, only reproducibility. This is a very enjoyable endeavor for me and I hope that some of you will get something out of the experiments, too.

Happy New Year!


Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 01, 2017, 07:44:17 PM
I did some simple measurements today now that I know it's safe to use the Endevco transducer without damaging it from over pressure. The results of these tests were surprisingly similar to the ones done with the Setra unit, but now I feel much more confident in the numbers. Anyhow, The photos show the profiles and numbers that were generated from some preliminary tests. It was nice to see that the pressure peaks are very similar between the two different power plants. I haven't bothered to do any temperature controlled tests yet because the room temperature was stable and I can measure the temperature of the gun frames and powerlets. The interval between shots was long enough for the temperature to equilabrate. These tests are being done now just to test the system and make sure that I'm on the right path.

This LeCroy scope is an old timer, but it's still capable of making many kinds of measurements and doing some advanced calculations that will be very useful and enlightening to me as I get more involved in this hacking project. For the moment I'm just interested in the test results of the 2 additional ports that were put into one the valve stems. The things to note right now are the rise time (10-90%) and the fall time (90-10%). The humps on the curves probably indicate the presence of 'critical flow' shock waves in the ports. The fall time is also interesting because of the difference between the 2 stems. The original stem (with the 2 new ports) is designated as channel 1. The other channel, A, is the unaltered stem. I'm going to have to design a test for measuring the transit time of a pellet through the barrel. This would give more meaning to the fall time.

These measurements are a new source of information to me. At this point I'm mostly in the speculation mode, but as time goes on I hope to understand CO2 power plants on a much higher level than I do now. Thanks for any interest that you may have in this project.
Title: Re: Hacking the Crosman Vigilante
Post by: dv8eod on January 01, 2017, 10:34:56 PM
Mister, you just keep posting and I'll keep reading!  ;)
This is probably the best testing thread I've seen on any forum. Actual data beats speculation any day.
Happy New Year to you also, and thanks again for posting your experiments.
Title: Re: Hacking the Crosman Vigilante
Post by: classicalgas on January 02, 2017, 03:35:42 PM
Very impressive test methodology and equipment!

What's the possibility that the multiple peaks in the pressure trace are hammer bounce ( multiple partial re-opening of the valve) rather than  pressure wave harmonics? Striker bounce is an established condition of airgun valves, and the time scale/decay looks about right for striker bounce.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 02, 2017, 04:22:18 PM
I'm less than a week into these pressure/time measurements, so I'm not ruling out any explanations for the differences between the curves of the 2 stems. The most interesting test for me at the moment is to find out how long a pellet might stay in the barrel after the valve is opened. One variable at a time.

Once the above information is recorded and digested I plan to install a micro accelerometer onto the hammer and see what shows up. Keep in mind that correlation is not always indicative of causation. I'll do the tests and those who wish to speculate on the results (including me) can have a free hand at it. I'm designing a transit time experiment this afternoon. There should be some results soon.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 05, 2017, 04:41:26 PM
I had plans for a more elaborate timing scheme for measuring the transit time of a pellet down the barrel, but opted out for the old trip wire method. It's crude, but should be accurate enough for a first approximation. The test is done with a pellet first being inserted into the forcing cone. A rubber seal from a sink faucet is then placed over each end of the barrel. The seals are part of a repair kit from the hardware store. I chose the gaskets for a good fit onto the barrel. The ends of the barrel then have a thin strip of aluminum foil taped into place. The tape allows the foil to be insulated from the metal barrel and also holds the foil in place. When the foils are secured in place the barrel can be adjusted to fit properly over the exit nozzle of the valve and held securely in place by the compression fitting in the barrel housing. This arrangement makes it easy to replace the foil after each test. I'll try to get the power supply and scope set up today.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 06, 2017, 04:41:16 PM
Today's test was supposed to measure the flight time of a pellet in the 10" barrel. The results were very instructive. It provided information on more than one level. First and foremost was the glaring reminder that if I don't take the time to set up a good experiment I'll usually end up with far less than what I want for results. The test also pointed out that I'm headed in the right direction if I stay with the trip wire method of timing. Included in the results were indications that much more is going on that may have significance in the overall way that the gas transfers it's energy to the pellet in a time/pressure envelope.

One of shortcomings of the set up was that I used foil instead of wire to start the timers. I wanted to use something that has very low tensile strength and still be relatively easy to mount and replace in a series of tests. I cut the foil into narrow strips and attached them across the ends of the barrel. Being inherently lazy, i didn't spend the time to cut them as narrow as I could have and the result was that they covered too much of the bore on each end. This actually turned out to be serendipitous. Instead of recording the pellet's transit time, the experiment ended up showing only the gas blow-by. It's transit time is on the order of 0.5 ms. This is only one measurement, of course, but it's a good start.

Since the pellet is already in the forcing cone when the test starts I can stick with foil at the breech to start the timer. The muzzle end can have either a wire, which will ignore the gas, or another foil if I just want to test the gas transit with or without a pellet in the barrel.

This may all seem sketchy at the moment, but I can see a myriad of experiments down the road. One that I want to try is to use a tee at the muzzle and put the pressure transducer in the arm of the tee and stub the tee's straight through end. This should allow me to measure the pressure/time curves of both the gas and pellet in the same shot. The pellet can then be captured in the stub. I may never get back to shooting at targets at this rate!


Title: Re: Hacking the Crosman Vigilante
Post by: kj on January 07, 2017, 09:08:38 AM
intresting stuff for sure. well if you never get back to shooting targets , at least you're having fun.

keep up the intresting work, thanks
kj
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 08, 2017, 08:04:25 AM
I finally got around to putting an accelerometer on one of the hammers. This is an Endevco 2250A Isotron. It's virtues are that it's light (0.4gm), easy to mount (super glue), and very easy to power up and get signals from. It's rated at +/- 500 G's with a resonance frequency of 80,000 Hz. I had to make a mounting block to keep the transducer approximately square to the forces at the point of impact. The block is aluminum and of insignificant added mass for these tests. I'll try to get a couple of experiments in later today.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on January 08, 2017, 12:16:52 PM
very interesting , im not sure what the hammer will tell you aside from how much bounce takes place?
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 08, 2017, 05:19:29 PM
I did a quick test on the accelerometer set up just to get things on scale. What's in the photo are the profiles of the hammer hitting the safety in the top trace and the hammer hitting the valve stem in the bottom trace. The powerlet was empty. These tests are just for curiosity and to 'sight in' the proper range settings. It's sort of like doing virtual target practice. Peak values in both traces are ~ 100 G's.

What I'm really after is the timing of the valve opening and closing and the timing and shapes of the pressure curves at the muzzle. The measurements can now start at the moment the hammer hits the stem. Much more data can be collected now without the need to stitch together the timeline. The different transducers can be simultaneously measured and the traces overlaid.

I hope this makes some sense about why I'm doing the accelerator/hammer experiments. More to come!


Title: Re: Hacking the Crosman Vigilante
Post by: ray1377 on January 08, 2017, 10:49:32 PM
I have a sneaky feeling that Crosman is about to sell a whole bunch of "Vigilante's" :)
Ray
Title: Re: Hacking the Crosman Vigilante
Post by: TleVta on January 09, 2017, 01:08:34 AM
Mine is ready whenever George is finished with his research.

(http://i1019.photobucket.com/albums/af318/tlevta/Vigilante_zpscw2ywcg6.jpeg) (http://s1019.photobucket.com/user/tlevta/media/Vigilante_zpscw2ywcg6.jpeg.html)
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 09, 2017, 04:04:25 PM
Things are coming together in bits and pieces. As can be seen in yesterday's photo,  dry firing the valve with an empty powerlet produced a much busier profile than the one shown today with a new powerlet installed. Things inside the frame seem to rattle around quite a lot when the powerplant isn't pressurized. Using the accelerometer to start the timing will be very useful for upcoming experiments.

I still have to get the timing curves for the pellet transit in the barrel. I can now use the hammer strike to drive the external trigger signal which then leaves two channels for data. I'm very interest in seeing when the pellet leaves the muzzle when plotted along with the pressure curve.

Of note in this post's photo is the lack of timing correlation between the trigger signal and the humps in the pressure curve. I'm back to the idea that the humps are the result of 'critical flow' shock waves in the valve stem ports. The stem used today is the factory one without the pair of 0.060" EDM'd ports. I'm still open to other interpretations that any of you my have. 
Title: Re: Hacking the Crosman Vigilante
Post by: dv8eod on January 09, 2017, 09:24:33 PM
I've been thinking about those residual humps since the last photo and can only speculate, but here is my hypothesis.

I would have to say that it's from the movement of the valve stem and here is my reasoning. They decrease gradually over the time period and the only 2 moving parts are the hammer and that stem. So it has to be one of them. I don't know if the hammer rests on the stem, but if the hammer is where the sensor is attached and it does rest on the stem, the unresolved humps would reflect drops that reduced by half at each point.
I'm thinking the CO2 is reopening the valve as it expands. It doesn't just move out the port, it pushes against all surfaces present. I visualize it as a group of people rushing to get out of a room. When everyone tries at the same time(the peak, a bunch get out until noone can fit through door. Then they back up (the drop and I guess rebound effect before pushing on the port side of the valve to reopen) and try again (another peak, but since so many got out the first time, the peak is  lower) until the door clogs  again. Repeat until the room is empty.
This might be the proof to lloyd-ss' theory of sonic choking. I haven't read that thread in awhile, but it sounds like what he was trying to explain.
Again, just grasping at straws here, please keep up the good work....
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 11, 2017, 09:57:12 PM
I've reconfigured the muzzle fittings from the previous arrangement and added the tee. I can now use the hammer signal to start the timer for the pressure gauge and capture the entire time/pressure profile of the valve opening up to when the pellet exits from the muzzle. This should give a much bigger and clearer picture about the sequence of events.

I'm also very interested in the muzzle crown and how it effects the pellet. The barrel choke is also part of that mix. I've brought an interesting instrument down from the attic that may open up a whole new investigation of what's going on as the pellet breaks free. As can be seen in the photo, the apparatus consists of a triggered air-gap light source and the electronics box that controls the lamp. The light source delivers a 50,000,000 candlepower flash with a duration of 500 billionths of a second. This can freeze things moving much faster than any conceivable airgun projectile. This light source will also allow me to a set up a schlieren optical system to record the pellet's and gas flow's shadowgraphs. I should be able to get some very interesting and informative images.

The number of irons that I have in the fire is growing quickly, but my interest in the information far exceeds the present projects. I appreciate that some of you are keeping up with the work so far.
Title: Re: Hacking the Crosman Vigilante
Post by: dv8eod on January 11, 2017, 11:06:52 PM
I am vastly enjoying the food for thought....  ;D
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on January 11, 2017, 11:52:05 PM
well I guess after you have collected all baselines, some spring changes and new date for comparison might be in order
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 12, 2017, 05:43:26 PM
I did a quick test this morning to tryout the new plumbing arrangement on the barrel. I haven't sorted out all the data yet, but I'll post what I have so that those interested can follow along see for yourselves. The bottom trace (1) can probably be recognized by now as the hammer/stem signal. It starts the timer. The top trace (2) is the pressure pulse with no pellet in the forcing cone. The middle trace (A) is with a pellet in the FC. All shots are taken with a blowout plug in the end of the plumbing. The plug is a small piece of ballistic putty to catch the pellet. The plug allows the pressure transducer to follow the entire gas pressure curve from the time that the valve opens until the pellet hits the plug and blows it out.

I've marked the point where the pellet is most likely to have passed by the pressure sensor which is at the muzzle. The transit time appears to be a little over 3 ms. This is all preliminary data and the experiment will have to be refined and further analyzed, but we have to start somewhere. Your guesses are as good as mine at this point. I'll try to do some more testing tonight.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 14, 2017, 04:39:26 PM
The pressure/time info is very useful in the overall scheme of things, but at the moment I'm most interested in the pellet transit time. While this timing info can be extracted from the P/T curves, I really wanted to get the transit time in a purer form. To that end I've added a Bruel & Kjaer type 8200 force transducer into the measurement mix. The instrument is compact and easy to mount in a variety of  ways. The device has a dynamic range of -225 lbf to +1225 lbf (-1000 N to +5000 N). This would mean that, if properly mounted, I can make direct impact measurements from any conceivable airgun projectile.

I did a quick test this morning to see how the output signal looks when mounted in the arrangement shown in the photo. The mounting block is a 2" x 2" x 5" piece of aluminum. The white plastic part is an end cap for 3/4" PVC pipe. The cap is filled with ballistic putty to capture the pellet. As can be seen on the scope screen, the signal from the force gauge is clear and unambiguous. When the force gauge trace is overlaid on the P/T curve much more meaningful info can be gathered.

The test results shown were done as a quick proof of concept run. I used the barrel with the tee because it was already on the pistol. This setup has a 4" extension on the straight- through part of the tee, so the timing info reflects the added distance from the real end if the barrel to the point plank placement of the force gauge.

Tonight I'll put the barrel from the trip wire experiment back into the housing and get much closer to the actual transit time. I'm also going to start setting up the Microflash system this weekend and these transit times will make it easier to get the pictures of the pellet/muzzle interactions. I've got no problem with math, but one of my mantras is "Don't calculate what you can measure".
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 15, 2017, 04:02:06 PM
I did some measurements this morning using the other 10" barrel without the tee and pressure sensor. This allowed the force sensor to be placed point blank against the muzzle. I found it interesting that the pellet transit time was very close to the original time estimated from the P/T curves. It's always nice to have two completely different ways of making a measurement agree closely with each other. There is still more info that can be gleaned from the P/T curves with further testing. Keep in mind that these test results are coming from the factory valve. The modified valve stem has still to be tested. It should interesting to see the difference between the two valves.

Next, I decided to change the barrel again and chose another 1077 barrel that hadn't been cut in half yet. The overall length is 20". The scope photo shows the transit time to be ~ 4.86 ms. This indicates that the pellet may still be accelerating when it gets to the muzzle. It will be interesting to put the pressure sensor at the muzzle and get some more P/T curves there. The implications with this longer barrel compared to the 10"are clear. All of this testing is starting to coalesce into something meaningful. I'll try to get some chronograph numbers later today. These tests are starting to compete with the high speed photography project for available time, but it will all come together soon, I hope.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 16, 2017, 05:44:55 PM
There has been some talk about hammer bounce being an issue with air guns. From what Ive seen in my tests so far (using the accelerometer) the bounce has been small and doesn't appear to open the valve enough, if at all, to allow much gas to escape. We're now dealing only with the Vigilante in these tests, but much of what can be learned here can also be applied to other airguns.

Rather than change springs right off, I was wondering I anyone has given thought to or actually tried applying Lenz's Law to make a magnetic damper? The NIB magnets these days are incredibly strong, readily available, and cheap. Maybe I'll give it a try.
Title: Re: Hacking the Crosman Vigilante
Post by: kj on January 17, 2017, 03:27:25 AM
wow, alot of info to take in. appreciate the time and effort your putting into this project. intrested to see the info about what happens as the pellet leaves the barrel.

yes alot of the info will be applicable to other airguns, and definitely the processes you used to get the info. i'd point out that just because the hammer in you set-up isn't bouncing enogh to waste gas/air , it's well documented that this does in fact happen with different types of guns with different plumbing. your idea of a magnetic damper is very intresting if you can find a way of controling it. many guns have different strength of springs and wieghts of the hammer , and others are adjustable. a practicle solution would have to be adjustable to account for the different variables present in other types of guns. unless of course you're just making it for yours.

very intresting stuff to be sure. looking forward to seeing your continued experiments. for some the shooting is the funest part, for some shooting and tinkering are equal, and for some tinkering is a larger part. lol

whatever happens, enjoy yourself, that's what it's about in the end.
kj
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 23, 2017, 07:32:29 PM
I've been moving forward on the electroplating setup and have been thinking more about doing electropolishing on barrels. Since there are several .177 straw barrels on the bench I'll start with one of them. The plan is to cut off sections about 1" long and then slit the pieces in half down the long way and then examine them with a microscope. If there are burrs on the rifling they should be easy to see. These sections can then be electropolished and reexamined to see how effective the treatment is. It will also be easy to nickel plate the sections to see how controllable the plating buildup can be done as an alternative to other methods of choking a barrel.

As usual, I've got too many projects going at once to ever be able to march a straight course. My wife says that I need direction and has offered to sew me a pair of blinkers that I can wear during the day. The photos show how the barrel is going to be sectioned for microscopic inspection. This detour will keep me going for a few days!
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on January 23, 2017, 10:35:21 PM
im starting to think you work in a  lab ;D
Title: Re: Hacking the Crosman Vigilante
Post by: TleVta on January 23, 2017, 10:39:09 PM
The plan is to cut off sections about 1" long and then slit the pieces in half down the long way and then examine them with a microscope. If there are burrs on the rifling they should be easy to see.

Brilliant. Carry on, Sir.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 24, 2017, 09:53:38 PM
After cutting a 6" barrel into 1" pieces I sliced one piece down the middle. One of these parts, as shown in the photo, will now go to the microscope so that we can see what a factory rifled barrel looks like up close.
What you see in the photo are dark strips where the lands are and lighter stripes where the groves are. I'll try to get some time tonight for a closeup inspection.

As an aside, last night, before any 1" sections were cut in half, I spent some time with the forcing cone end section and pushed some pellets slowly through the piece with a small stick from the kitchen. I've done this before with an original 6" barrel and it was only somewhat informative. Now, with this short piece, the feel was completely different. The lower mass of the short piece can't damp out vibrations of the pellet's slow travel and I didn't have to press as hard to hold and support the mass of the full barrel. The vibration sensations of this short barrel piece were considerably enhances and the feel of the grittiness during the push was striking. This experience is stated for whatever use others might care to infer from it.
Title: Re: Hacking the Crosman Vigilante
Post by: Hobbyman2007 on January 25, 2017, 08:01:07 PM
That's quite the collection of tools you have there. Very informative , keep it up .
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 25, 2017, 08:07:55 PM
I got the microscope setup and took a few photos to see what things would look like. The depth of field is really shallow, so it might take some imagination to figure out what you're looking at. If these images are compared to the previous postings photo it might be more clear about what's going on. I have some focus stacking software that will really cleanup these images, I just have to figure out how to use it again. If I can get it going the photos will be dramatically improved. I can already see why the pellets felt gritty going through the barrel sections the other night. I have an excellent German Storz/Hopkins borescope, but it can't compare to a good cross section examination with a metallurgical microscope and a focus stacked image. Looks like I've set myself up for more projects.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on January 25, 2017, 08:14:49 PM
very nice resolution.. interesting !
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 30, 2017, 09:55:49 PM
This photo today was quite a challenge to get. The half section of the barrel is a curved surface and far beyond the focus depth of the microscope objective. The depth of field is about 2 microns. Therefor, to get this photo it took a stack of 12 images to get what you see. It's been some time since I last used this equipment to do focus stacking, so I expect to see  improvement in the images as I play with it more. Please bear with me.

The purpose of the imaging project is to have a tool to evaluate the presence and extent of any burrs and other anomalies that might be left from the rifling method. Some of the artifacts of that process are obvious and others are a mystery to me at the moment.  I'm going to have to get some metallurgy books down and dust them off. I now have a worthy project for applying some electropolishing experiments.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on January 30, 2017, 10:17:04 PM
looks like the surface of a planet ! be interesting to see the result of the polishing , both looks and accuracy
Title: Re: Hacking the Crosman Vigilante
Post by: dv8eod on January 31, 2017, 02:04:18 AM
The first ? on the right is a scratch from a bore gauge, the ? on the left appears to be a cutter skip, and the second ? on the right I can't tell if it's a bump or a gouge. If it's a bump, then I would have to say that a piece of swarf was ironed on to the land. Not sure what the cause would be if it's a gouge.
Airgun barrels are not as hard as PB barrels so I'm not surprised at the quality of the rifling. Most start out life as hydraulic line.
With that in mind, I'm curious to know what you will be using for the electropolishing and what you will be replacing the missing material with during the electroplating.
I spent five years drilling, reaming, rifling, turning and surface finishing gun barrels for the PB manufacturer here in town before moving on to bigger and better things.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on February 01, 2017, 02:58:05 PM
Now that the evidence of burrs and other artifacts of rifling can be seen, it will be interesting to see if they can be reduced or even eliminated from the Vigilante barrels. Being new to the process of electropolishing I can only assess the benefits of the method from what I've read and seen on the internet. I am familiar with the electroplating process. It appears that by reversing the electrode polarity and changing the electrolyte from plating solutions to electropolishing solutions the results should work as well as the literature describes. The most interesting thing about electropolishing to me is that it will selectively remove the burrs and nonuniform surfaces and yet have minimal effect on flat and uniform surfaces. It shouldn't be difficult to control this process if the setup is done properly. I have plenty of parts to practice with.

I'm not anticipating the need to actually replace any material to the barrel after electropolishing. There should be little to no material removed from the truly flat surfaces of the lands and groves. There could be some rounding of the top edges of the lands, but that would simply tend to round the corners slightly. From what I've seen of various rifling images on the internet it may be an asset to have these edges slightly rounded.

The electroplating process that I've mentioned earlier will be an experiment to see if the muzzle can be choked controllably by building up a layer of plated nickel instead of mechanically inducing a choke by reducing the diameter of the muzzle. To build up a surface by a thousandth or two should be easy to control. We'll see.
Title: Re: Hacking the Crosman Vigilante
Post by: dv8eod on February 01, 2017, 03:40:18 PM
Electropolishing uses an acid or combination of acids in conjunction with an electrical current over a set amount of time to remove material. Both lands and grooves along with the burrs will be consumed in the process. The microns removed from an airgun barrel may be a little more critical for sealing purposes. It maybe effective for reducing the friction coefficient, though, if not too much is removed.
Personally, I believe firelapping would be more efficient and economical given the safety measures, disposal requirements, availability of chemicals, and the need for a high voltage generator.
It took 600v per barrel to electropolish using phosphoric, sulfuric, and chromic acids mixed over a 10 minute time frame. That generated a lot of heat and vaporized acids. We had specialised tanks, jigs, and ventilation scrubbers to try to contain everything and still had safety issues arise.

It dawned on me after my last post that your sample might have been swaged. If that's the case, the ? on the left and the last on the right are from metal chips being on the mandrel when the hammers struck. The burrs would have been caused from a worn out and possibly chipped mandrel.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on February 01, 2017, 04:33:25 PM
Just to keep things in perspective here I'll point out that sulfuric and phosphoric acids are readily available at Home Depot. The chromic acid is optional in many electrolyte recipes. I don't plan on doing a full immersion of the barrel because I'm only interested in polishing the bore. This will require only a few CC's of electrolyte to fill the barrel. Disposal of an ounce or so will be a nonissue because the H2SO4 is sold by the quart as a drain cleaner and the H3PO4 is sold by the quart as a general cleaner for tile and grout, etc.

The process is basically controlled by current density, temperature, and geometry. I plan to use the carbon fiber brush technique. This method will only require about 6 to 12 volts in order to maintain the desired current for a controlled rate of material removal. The surface area to be treated is very small.

This process seem pretty tame at these levels, so I feel obligated to do some experiments and then report the results.
Title: Re: Hacking the Crosman Vigilante
Post by: dv8eod on February 01, 2017, 05:03:37 PM
Please don't take it that I'm trying to talk you out of your endeavors. I'm looking forward to seeing your results as much as the rest. I was merely stating my experience with the process.
Title: Re: Hacking the Crosman Vigilante
Post by: classicalgas on February 04, 2017, 03:25:43 PM
Fascinating stuff, and wonderful test equipment.

A couple comments that may be useful.

As a swinging hammer driven, inline with the bore,flow  through spool  valve, the Vigi is almost unique in the airgun world. The only gun  similar ( to  my knowledge) was the crosman 1100 shotgun.

 Striker driven, poppet valve, over/under arrangements are used in 90+% of  gas guns  (co2, pcp, pump up) airguns in production, so it's likely most of the valve dynamics you are seeing will  not apply to many airguns.Even the few swinging hammer guns are over/under(180 degree flow path) and poppet valve. I'm hoping you'll fit your test equipment to a more typical airgun at some point, and compare results. The one other through the spool valve , in production gun I'm aware of is the 850 magnum (and it's variants) That might be an interesting gun for a comparison study, it's striker driven.

Electro polishing  the  bore wont fix the biggest problem with barrels...inconsistent diameter of the bore. The traditional lead lap, cast in place and loaded with fine abrasive, bumped up to expand the lap as the bore is worked in, does even out the bore, taking out the tight spots as well as smoothing out tooling marks.  Real world tests, over hundreds of years, have proven the lapping method to be effective in increasing accuracy. Comparison micro-photographs of a lapped bore and a as tooled bore would be most interesting.
Title: Re: Hacking the Crosman Vigilante
Post by: classicalgas on February 04, 2017, 03:38:13 PM
Addendum, re the bore constriction issue in airguns. In my experience it's common to find the bore of a break barrel springer so tight in the breechblock area, that once forced past that constriction, the  pellet takes  almost no pressure on the rod to move it to the muzzle (or choke) The choke( if any) is there as a crutch, to get a reasonably good fit to the swaged down pellet, and get decent accuracy.

Fire lapping is an expedient work around, and often increases the guns accuracy substantially, though  not as much as skilled hand lapping.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on February 04, 2017, 09:44:40 PM
I was attempting to make some room on one of my experiment benches awhile back and ran across a couple of 1 uCi Am 241 sources from cannibalized smoke detectors. Recognizing an opportunity to avoid further efforts at organization, I decided to distract myself with them.

I needed to find a interesting direction to wander off in, so I did a Google image search for the radiation spectrum of Am 241. What caught my eye was the low energy x-ray florescence lines generated by the decay products. They are bunched nicely below 30 Kev and looked like a good substitute for a low energy, low power x-ray tube. The ~ 59 Kev line looked helpful, too. It's interesting to see how many versions of the spectrum there are depending on the type of detector used.

Since I'd previously purchased one of the Russian proportional counting tubes from eBay, this seemed as good a time as any to test it. It worked, but not very well. It will resolve some of the lower energy peaks, but really isn't up to the job. An earlier purchase of a double windowed proportional tube turned out to be a complete dud. The Be windows can still be salvaged, though. I switched the Russian tube out for a tried and true GE 10-SPG tube.

Anyhow, since this experiment had been lashed together in a couple of hours with no intention of being quantitative, I'll spare you guys the details of the measurements and just post a few of the images to give you an idea of what it can do. They show the basic arrangement of the 2 sources pointing away from the Be windowed detector and aimed at the target. The images indicate that ~ 2 uCi of Am 241 can be used as an x-ray source for making a crude XRF (X-Ray Fluorescence) system. Also, please keep in mind that these AM 241 sources  emit almost no radiation compared to some household items and the potassium salt used in water softeners. I will not respond to any Chicken Little warnings.

I'm going to reconstruct the basic system for use in analyzing the alloys of pellets and straw barrels. This will allow for a reproducible irradiating source that can be use with a wide assortment of other detectors The set-up was only a proof of concept quickie. I'm a sucker for good deals on unidentified metals in almost any form. There can be huge savings compared to buying identified and labeled stuff.

I'll post progress as the system goes back together. Yes, this is all part of hacking the Vigilante.

Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on February 05, 2017, 06:15:22 PM
I've been thinking about the variations in the resistance that a pellet has when pushed through a barrel. It appears that I'm not the only one who's noticed these variations, though I've not seen any attempt to quantify the effects. There must be someone that's done it, but I can't recall seeing any actual numbers having been applied to the activity. I've decided that it would be more interesting to make the measurements than search for them on the web.

The experiment is relatively easy to set up. I'll be using a Honeywell model 3167 tension/compression pancake load cell. I looked in the attic and found a collection of them with various load ratings from 25 lbs to 300 lbs. I'll start with a 25 lb cell which will give the best range for this test (I think). I'll use the 5 lb and 10 lb Toledo weights for initial calibration tests. The cell output will be a measured by a Vishay V/E -20A strain gauge indicator. The output of the cell can be read dynamically by this instrument and recorded. My choice for recording this data will be a simple, but hopefully effective, Lascar EL-USB-3 voltage data logger. All of these instruments have been sitting around for years, so I hope they still work properly.

I'll have to do some machining to get things started, but it should be minimal.  I'll use the mill as a testbed. It will only have to hold the pusher ram and barrel in good axial alignment and I'll use the fine feed wheel to feed the quill. If this experiment works it will be a good way to standardize and measure the effectiveness of various bore treatments without sectioning them first.

I'll probably be spirited away from the garage by my wife when the Big Game starts. I'll do what I can in the mean time.

The photos show the equipment that will be used for this first attempt.


Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on February 06, 2017, 12:00:53 AM
I got the preliminary testing arrangement set up on the mill. Everything is working properly so I can start doing some pellet pushing. I'll have to rearrange the parts to do the test, but I wanted to be sure that it was going to work before I went to the effort of making a couple of fixtures to mount everything. As can be seen in the photo, the data logger has been superseded by a scope. The data logger needs to be read by a computer after collecting the logged data so there is no real time info available. The scope is real time and much more flexible for this experiment. I should be able to start the real testing by this evening unless I get distracted again.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on February 06, 2017, 10:05:19 PM
I think that this pellet pushing experiment is going to be very instructive (to me, at least). I forgot how enjoyable it is to play with load cells. I got the system working as a proof of concept rather easily. A fixture was made on the lathe that allows the short barrel sections to be held in good axial alignment with the pusher. the pusher is made from a knitting needle that was pilfered from my wife's sewing room. A short piece of it fits into the drill chuck on the mill and the other piece of it is used to finish pushing the pellet out the exit end of the barrel after the test. There are some modifications that I want to make in the cell fixture, but that can be done later.

The scope trace shows the applied force over time. It amounts to a surprisingly low peak value of about 1 pound. This was lower than anticipated. The rest of the trace shows the roughness of the short piece of barrel section. The pellets are CP Pointed. The drawback of this method of pushing the pellet through is that it's hard to maintain a really constant feed rate by hand turning the wheel. This can all be addressed down the road. There can be some stick-slip anomalies in the trace, but they don't dominate the data. The main thing is that the release pressure in the forcing cone is very real. The Owon scope is no LeCroy, but it's a lot better than those nasty little data loggers.

I'll put some more thought into the project and consider making a constant velocity pusher that will be able to do a 10" barrel in one pass.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on February 08, 2017, 09:00:21 PM
I decided to move the pellet pusher from the mill over to the lathe. The lathe has a 40" bed, so it won't run out of room with any barrel that I'll ever see. The other advantage of the lathe is that I can set the pusher to run at a selected constant speed. This will eliminate the artifacts of stick-slip conditions from the data.

In order that the lathe carriage can moved along the bed it was necessary to make a fixture that would allow the chuck the rotate while the pusher remained free of the chucks rotation. The fixture in the chuck has a ball bearing pressed into it to allow this to happen. The load cell is mounted in a 5C collet. The collet holder is held in the compound rest which in turn moves along with the carriage.

I plan to make some smooth bore barrels to act as standards for these measurements. It will be interesting to see how sensitive this method can be. Since there seems to be no other instrumented way to do this test (as far as I know), we can start with this arrangement. I look forward to how others will approach it.

The 1 pound breakaway force at the breech that I've seen in the first test can also be converted to a force of about 12 psi for comparison to tests of other caliber pellets.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on February 09, 2017, 09:20:43 PM
I've started to do some testing with the new horizontal pellet pusher in the lathe. This is all preliminary stuff, but the indications are that it will be a good way to test the smoothness and uniformity of a barrel.

The photo shows three simple tests. The were all done with .177 cal CPHP pellets.  The bottom trace (A) is a pellet pushed through a smooth bore Daisy 1200 BB barrel. The middle trace (B) is the pusher in the same barrel, but without a pellet. This represents the total system noise. The top trace (RED) is a pellet pushed through a 10" section of a 1077 barrel.

The measurement travel is about 1" of randomly picked area in each barrel. There's lots more testing to do, but I'm confident that good information will come from continued use of this method. The pellet and barrel in any gun is where the rubber meets the road.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on February 10, 2017, 04:32:35 PM
I did a quick test this morning to see if putting a drop of 3 in 1 oil into the barrel before pushing the pellet would change anything. Well, of course it should, but I needed to see for myself. The photo shows the results. The lower trace (A) was without the oil and the top trace (B) was with a drop just in front of the pellet. Both pellets started in approximately the same inch of barrel just after the forcing cone.

This test could be a study in lubricants down the road. You've got to start your day doing something. I'm really pleased with the prospects for pellet pushing.
Title: Re: Hacking the Crosman Vigilante
Post by: AmBraCol on February 11, 2017, 10:37:11 AM
George, just to toss another variable into the mix - have you checked the size of the pellets you're using? Pellets from the same can can vary quite a bit from each other. 

http://pelletgage.com/ (http://pelletgage.com/)

Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on February 11, 2017, 09:24:29 PM
I'm aware of the fact that pellets can have different dimensions even within the same can or box. I've avoided attaching real numbers to many of my tests because of these variances. I'm most interested in the comparative results of these preliminarily experimental findings for the moment. I'm just looking for results that will head me into interesting areas. Much of what I'm doing now is being put out there so that others will be able to construct their own ideas about what the experiments might mean. I don't have nearly enough data to draw any numerical conclusions yet.

Most of what I've seen posted anywhere so far has been in the form of spreadsheets and chronograph results. Very little in the way of actual instrumented testing is available about airguns that I'm aware of. Please use this thread to post those results if you have any. It may save me a great amount of time and effort if my experiments are redundant.


Title: Re: Hacking the Crosman Vigilante
Post by: AmBraCol on February 11, 2017, 11:06:19 PM
I'm aware of the fact that pellets can have different dimensions even within the same can or box. I've avoided attaching real numbers to many of my tests because of these variances. I'm most interested in the comparative results of these preliminarily experimental findings for the moment. I'm just looking for results that will head me into interesting areas. Much of what I'm doing now is being put out there so that others will be able to construct their own ideas about what the experiments might mean. I don't have nearly enough data to draw any numerical conclusions yet.

Most of what I've seen posted anywhere so far has been in the form of spreadsheets and chronograph results. Very little in the way of actual instrumented testing is available about airguns that I'm aware of. Please use this thread to post those results if you have any. It may save me a great amount of time and effort if my experiments are redundant.

To the best of my knowledge, your experiments are anything BUT redundant.   :D  I don't know enough to be aware of all that I'm seeing, but find it fascinating none the less. Thanks for sharing your journey with us.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on February 12, 2017, 11:06:53 PM

It came to me today that I've totally neglected the aspect of controlling the loudness of airgun reports. The topic was one of my original quests when I started this adventure and then got side tracked during the tsunami of other tests and measurements. At this point I'll just have to admit that I have no control over what I want to do next. There are many pieces to the puzzle of how airguns work, but if we keep collecting the pieces as we go I think that some of us will benefit when the dust settles. A clearer picture may then be seen. I'll just park my information here until things appear to be made from whole cloth.

Sound and vibration are next to come. Stay tuned (pun).


Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on February 19, 2017, 10:04:20 PM
I got diverted back to the electropolishing on the barrel. A discussion with my buddy Bruce got him fired up about the process, too. One of the topics was about how to build and use  a carbon fiber (CF) brush as an alternative to doing a dip bath approach. In the interim  Bruce put together a brush and brought it over to my place to test it on some SS weld coupons that he brought along for testing. I had the acid electrolyte components so we mixed them up for a test run of his CF brush  project. The results were strikingly good.

Since the electrolyte was mixed it seemed like the right time to get into the barrel treatment I had been planing. Two of the short barrel cross sections were polished using the dip method. I was able to partially dip them into the solution and just treat part of the barrel as a comparison test. The images show the transition area along with the treated and untreated areas. The photos are of a barrel section that was polished for 1 minute. The grain structure of the lands is very clearly seen. The tool marks have dissapeared.

The features in the images are quite small. The step height between grooves and lands is less than .002". The actual height is difficult to measure accurately by mechanical means. A first approximation can be guessed at with a small hole gauge, but it's still a guess. Contact measurements at this scale tend to deform the surfaces being measured and will introduce errors. I'll probably end up mounting the barrel section in a metallurgical mounting press and then use an optical micrometer to get good numbers.

In the mean time it is sufficient to see that the polishing can controllably remove surface material selectively in the range of a couple of microns. The machine marks left by the rifling tool leaves marks on top of the lands that are down in the microns range. I'll use a surface profilometer at some point to determine the real numbers. Right now I'm only interested in the grosser aspects of the polishing process.

The electrolyte mix that was used to do this work was mixed to do the best work on stainless steel. It's a very aggressive recipe to be using on what might be mild steel of the barrel. I'll do some more research and see what the best mix will be for steel barrels.

On another front, the sheet of Scotchlite 680 that was ordered has now arrived which will allow the shadowgraph experiments to proceed. I'm getting pretty excited to see the results.

As an aside, I've been working with the focus stacking software and getting better with it as I go. I'm adding a photo of a single frame of the stack of about 25 images to illustrate the power of this technique. Keep in mind that these stacks are imaging an arcing semicircle formed by the barrel.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on February 24, 2017, 03:58:03 PM
I've been puzzling over the best method for measuring the lands and grooves of the cross sectioned barrels. The metallurgical mount and polish technique is the best method, but it sure is time consuming. After pondering the project over a few beers it came to me that there was a linear displacement transducer instrument somewhere in one of the darker corners of the attic. Braving the darkest sanctums of my techno-repository with a flashlight, I was able to recover the device.

The virtue of this particular instrument is it's ability to make very accurate measurements down to 1 micron. What makes it different from the typical precision micrometer is the force of the probe against the anvil. The measurement specification for most micrometers requires a load force between the spindle and anvil to be .5 to 1 N. This amounts to a force of ~ 50 to 100 grams. Applying this load also requires that the spindle be rotated while applying the force. This is an undesirable situation for the measurements that I want to make. These high forces also make it difficult, if not impossible, to measure the diameter of heads and skirts of many types of pellets with any accuracy or reproducibility.

As can be seen in the photos, this linear transducer has a loading force of only 2.5 grams! The probe doesn't rotate and the anvil and probe can be customized to accommodate barrel sections, pellets, and other small featured items. 
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on February 27, 2017, 08:40:40 PM
I've been giving some thought to valve dwell time and pellet transit time in various barrel lengths. For clarity I'd like to say that, from what I've read, it seems that in airgun vernacular the 'lock time' is the same as what I'm referring to as 'transit time'. This is a holdover from charged particle physics in my case. If the terms are not usefully interchangeable please set me straight.

Anyhow, what I've noticed in the previously posted O-scope traces is that what I thought was the first hammer bounce is more likely to be the rebound of the valve stem. The timing is consistent at very close to being 4 ms and the profile is shaped differently from the hammer strike. If this is correct it will be very useful when relating it to a pellet's transit time.

There was a comment that some of the things that I'm measuring are not generally transferable to other airgun platforms. I'm somewhat nonplussed by this comment because the measurements that I'm making can be easily rearranged to suit the requirements of other airguns. It's just a matter of choosing the right transducers and readouts to get the numbers that you want.  This brings me back to my mantra: 'Don't calculate what you can measure'. Nothing against spreadsheets, but.....


Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on March 06, 2017, 05:33:01 PM
I thought that it was time to take another look at choking a straw barrel. The last time that I played with the lathe and knurling tool on a barrel it was to confirm that the technique was viable and just used the test as an exercise in making the measurements as accurately as I could. As previously posted, the knurling worked quite well to reduce the bore diameter at the muzzle.

Since then I've read a lot of information about the the process and very little about any measured results. I've also made some dimensional measurements of the lands and groves. Considering how small the step is between the grooves and lands, I now had a target to aim for (pun) when deciding how much choke to apply. I chose 1/2 mil (0.0005") as a start. The bore was reduced from .1778" to .1773". The force involved to accomplish that was surprisingly low. At some point I should construct a micro load cell in order to attach a number to this force. All in good time. Right now I just wanted to measure the dimensional change in the bore and see the effects on a target.

Anyhow, it was finally time to test the results. I chose to do the preliminary tests with CP Destroyers and CP Pointed pellets. I already knew that the CP Pointed ones were a gross disappointment from previous tests. The Destroyers always seemed to produce favorable results in the assortment of barrels that I've used. Could a choke improve the earlier results and make the Vigilante less fussy about what its fed?

The photos show the difference between the two pellets when shot through the unchoked and choked 10" barrel. The shots were fired from 15 feet. I used each quadrant to separate the results of 10 shots per group and keep them on the same target sheet. One quadrant of the pre-choked Pointed group has only 5 shots. The test in the last quadrant of the CP Pointed choked group was not done because of low pressure.

There are a lot of other measurements still to be made, but this is where we are now. I think I see an improvement, but I'll leave that up to you guys to make further assessments.

As an aside, I'd like to add that a ten shot string with the powerlet temperature adjusted to 82º F gave an average velocity of 596.4 fps using the CP pointed pellets. I'll try boosting the temp to 85º F and see what the difference between the CP Destroyer and CP Pointed comes out to be.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on March 06, 2017, 05:57:10 PM
the results are looking very promising.. i wonder if a longer pellet would do any better
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on March 08, 2017, 09:45:26 PM
Now that I've become so enamored with the idea of pushing pellets through barrels to test drag characteristics it seems practical to relieve the lathe from having to be tied up for the tests. I've had a universal testing machine sitting in the corner of the garage for a long time just taking up space and collecting dust. It's time has come to earn its keep. This is actually the type of machine that should be used for this type of testing and also many other tests that I'm now considering. Who knew that airguns would become this recreational?

The machine is rated at 10 kN ( one metric ton) for both compression and tension. It would be considered rather lightweight as far as universal testers go, but will work out perfectly for my airgun plans. By changing load cells it will be able to measure down into the grams region. These expanded capabilities are getting very interesting (to me).
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on March 08, 2017, 09:48:13 PM
you have 1 of everything , this is crazy lol
Title: Re: Hacking the Crosman Vigilante
Post by: AmBraCol on March 09, 2017, 09:50:36 AM
These expanded capabilities are getting very interesting (to me).

AND to some of us sitters-by...  What equipment do you NOT have "sitting in the corner of the garage..."?   ;D
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on March 16, 2017, 05:01:25 PM
I decided to put the parts together and see what the Vigilante would look like in full dress. I also wanted to have something to shoot targets with. The new knurled muzzle choke is considerably more accurate than the stock version. This is a pleasing outcome and worth the effort spent so far. There's still lots more to test and measure, but I'll get back to that soon enough.

I've left the knurled part of the barrel extending out past the housing extension. That's going to be my signature on the barrels that have been tuned and choked.   
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on March 28, 2017, 10:27:49 PM
I've been spending some time actually shooting a couple of Vigilantes at targets. The barrel with the knurled choke seemed to work better than the non-knurled ones, but I wanted to see what the difference would be if a new barrel was crowned differently than usual. Then it could be compared to a choked one and the two methods could be compared. This test could actually be expanded because I'm using a Crosman 1077 barrel to make two new 10" barrels. The nice thing about this is being able to make two 10" muzzles from the middle of one 20" barrel. That means that the two muzzles are literally identical because they are from the same point in the middle of the parent 20" barrel.

Since the bench testing and measurements so far have not required any special need for anything more than generic pellets, I've collected only the readily available Crosman Premier tins from Amazon and Walmart. These include destroyers, pointed, and hollow points. When I'd done some target shooting in the past with these different pellets, the Vigilante showed a marked preference for the destroyers in any of the previous barrels. The pointed and hollow point pellets were consistently producing groups(?) with many flyers that made shooting them unenjoyable, to say the least. The destroyers always seem to give good results at my standard 15" target range, though even they weren't without the odd flyer.

The photo shows the results of the new muzzle crowning method. To keep the different pellets on the same target, I shoot each different type at one quadrant and then rotate the target. That way I can get at least 4 different tests on the same piece of paper and not have to re-aim the gun. Each of the 3 groups are 10 shots. That's 30 shots without a flyer!

I'm rather stunned by the results and don't really have an explanation yet. I hesitate to do the choke knurling at this point until I can determine what's really happening. The target is at the usual 15' and the gun is clamped in a vise in order to eliminate any marksmanship requirements. I readily admit to being a lousy shooter.


Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on March 28, 2017, 10:35:40 PM
thats really good to hear.., id love to see sight assisted 10 yrds
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on April 05, 2017, 03:00:30 PM
The progress continues with the Vigilante hack. The results of the muzzle crown and knurled choke testing demonstrate that accuracy can be significantly improved and the number of flyers can be greatly reduced even with pellets that don't work well with the factory barrel. More testing needs to be done to find out how these improvements came about. The high speed muzzle shadowgraphs will be a great help in sorting some of these things out. I'll have to move that testing back up the list of experiments.

The barrel and housing design has stabilized for the time being and I've decided to build up some units as a direct replacement of the factory one.  These barrels can be switched over with just 1 screw. I'm listing these new type barrels on eBay if anyone is interested in acquiring one. Just look for "Vigilante upgrade".
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on April 05, 2017, 04:01:37 PM
the ebay mod looks great and adresses more issues than i thought, very cool
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on April 13, 2017, 10:38:51 PM
Now that I've been doing some actual shooting at targets it's become obvious to me that I can't hit much of anything if I use the factory sights. After buying a cheap red dot sight the possibility of being able to hit what I'm aim at seemed close at hand. The problem is that the Vigilante is made more for a tactical look than function. The barrel rail, even with the new rigid stabilization, is not designed to accept much in the way of add-on sights. Those of you that have vigilantes know how limited the top mount really is.

I decided to mill off the front sight and machine a new tactical mount that could be rigidly fixed to the rail. The new mount now allows a sight to be moved forward enough to make room for easy actuation of the barrel latch. The photos show the new arrangement on one of my testbed revolvers.

There are still plenty of things that can be done to improve the overall performance of the Vigilante. I'm glade that I've taken some time off from testing so that I can make sure the things I've been posting about have some relevance to the real world of actually using the gun for target practice.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on April 18, 2017, 04:52:09 PM
The the top rail was a good start in the direction of adding some form of sight, but it was left wanting. The original rail was machined from nylon (it was handy), but was a bad choice because of it's flexibility. When it was attached to the barrel housing rib and the plastic cheap sight was added, it really wasn't stable at all. The Gamo sight alone seemed to be made from recycled rubber bands. That's OK, though, I just needed a place to start.

This weekend's project was to buy a better sight and machine a new rail. The results come out much more like what I had in mind. The rail is machined out of aluminum and is much more solid. Also, the red dot scope is far superior to the first one. The Barska is still a low-end device, but will be satisfactory for the time being if it continues to work properly. Overall, the pistol is considerably stiffer than when it came out of the box. More can still be done in that direction.

I'm working on the ergonomics of this gun to make it friendlier to a guy who is a lousy shot. The next step is to add a forearm grip under the barrel housing to asset in two handed aiming. The vigilante is getting closer to becoming a carbine. Plans are in the works for a shoulder stock. 
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on April 18, 2017, 05:30:21 PM
wow, this is awesome ! id love to see it as a carbine , and be equally interested in seeing what a competition pistol shooter could squeeze from this design !
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on April 20, 2017, 07:06:26 PM
A Delrin forearm has made the vigilante a new gun and was worth the time needed to machine it. The pistol now handles unusually well with the a forward grip. The overall increase in weight, even when moving the sight all the way forward, is easily balanced without needing a sandbag or rest. When the shoulder stock is added I'll have a mini-carbine. I may finally be able to hit something that I aim at!

I originally was looking at getting a Crosman 2240 and hacking it, but I didn't want just a single shot gun. These Vigilantes are turning into the pistol I've been looking for. There's much more to do and each step forward makes it a more desirable gun for me. The next step is to cut off most of the protruding trigger and just use the seer to fire the gun as a single action only repeater. It's not going to be a 'lawyer trigger' anymore, but I'm betting that it will improve my shooting accuracy considerably.

I'd like to again say thanks to all of you who have been patiently following this project and for all of the positive and encouraging comments. I'm not much of a conversationalist in a forum venue, but I do pay attention to all of your comments and replies.



Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on April 21, 2017, 12:58:03 AM
Extra Photo.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on April 21, 2017, 02:00:36 AM
Extra Photo.


looks great , nice knurls
Title: Re: Hacking the Crosman Vigilante
Post by: AmBraCol on April 22, 2017, 09:17:56 AM
Looking forward to seeing it set up as a carbine.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on April 24, 2017, 11:08:35 PM
There has been a lot of discussion about "barrel harmonics" in some of the places that I've been reading lately. There is much conjecture, but very little in the way of testing and measurements so far. Maybe I'm spending time in the wrong places. At any rate, I've decided to put a few tests together and try to get some reasonable empirical information about the barrels I'm using. The tests are actually pretty straight forward, though not always simple.

My plan is to test the natural frequencies of the 10" barrels and then see what can be done to make sure that the vibration components that might interfere with a gun's accuracy can be brought under control. I've spent a lot of time with projects that involve sound and vibration which require interesting methods to evaluate various devices. Over the years these projects have required quite a bit of specialized hardware and methods to apply the instruments.

One of my pet instruments is a Bruel & kjaer Complex Modulus Apparatus. It's an old type 3930 and has been sitting on a bookshelf in my lair for quite a while. Some instruments are just to beautiful to hide in the attic or the garage's loft. I realize that it's all in the eyes of the beholder, but I have my weaknesses. Anyhow, I thought that some of you folks might be interested (amused?) in the next potential distraction that I'm probably going to get all caught up in now. This diversion will probably get me back to the acoustics tests that I want to do.

The photos show the 3930 with a 10" barrel mounted in the test position. I'll add more info as things progress.
Title: Re: Hacking the Crosman Vigilante
Post by: kj on April 25, 2017, 07:10:45 AM
wow, you sure are putting in some work. on barrel harmonics. they affect longer skinnier barrels most. as the barrel gets shorter and/or thicker, it becomes less suscepible to the effects of harmonics. basically the barrel whips about and affecys where ot's actually pointing as the projectile leaves the barrel. sleeving and/or tensioning the barrel are common ways to lessen the harmonic effect. indexing  barrels is an attempt to get the pellet to leave the barrel at the top or bottom, rather than off to a side. i'm not sure if this last bit is completely due to harmonics, perhaps the barrel crown or manufacture.

you'll probably find more about harmonics in relation to powder burners (pb).

peace
kj
Title: Re: Hacking the Crosman Vigilante
Post by: dv8eod on April 28, 2017, 12:06:49 AM
Some reading I thought you might enjoy, if it will post.
Title: Re: Hacking the Crosman Vigilante
Post by: AmBraCol on April 28, 2017, 09:40:45 AM
Some reading I thought you might enjoy, if it will post.

I'm getting the error message that its "not a real PDF" or "it may not be properly encoded".
Title: Re: Hacking the Crosman Vigilante
Post by: dv8eod on April 29, 2017, 05:22:33 PM
Sorry guys, when I try to attach it from the computer, it says that the file is too large. If it can be downloaded, try renaming it by removing "%20" and replacing it with a single space. Can't guarantee that it will work.
If you really want a copy, PM me your email address.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on April 30, 2017, 07:06:55 PM
Doing some vibration measurements on the 10" barrels that I'm using has been very instructive. Since the Complex Modulus Apparatus (CMA) is a good experimental representation of a clamped end barrel with no intermediary supports it can be studied as a clamped end, single tine, tuning fork. This model offers an easy way to get into the physics of barrel harmonics. I have to start somewhere.

The measurements so far show that the natural frequency of each of the 4 sample barrels is 107 HZ +/- ~1HZ @ ~70º F. The 2nd harmonic is more than 6 times higher in frequency and of very low amplitude and can be ignored for the time being. This is still a proof of concept experiment, so I'm trying to make things easy. As an aside, if I put my ear close to the end of the barrel when it's being driven the tone can be heard, though I don't see any movement without using magnification.

The CMA can now be mounted sideways and a fixture arranged to allow barrels of different lengths to be measured by actually firing the gun at a target. Barrel rings and different damping materials can then be experimented with. The CMA's non-contact measurements will simplify many of the calculations needed to evaluate the data.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on May 06, 2017, 04:42:28 PM
The Vigilante carbine is making good progress. Right now I'm fitting a Crosman stock to the pistol by doing some milling and carving. It's crude in the present form, but it snaps into place nicely and with some more work I'll be able to bolt it into place solidly. The stock will probably be modified to allow just one of the side grips to be removed in order to allow access to the powerlet without having to remove the whole stock. The grip can then be snapped back into place.

I've already put many clips through the new pistol arrangement and the overall improvement in feel and accuracy is remarkable. The black box that is shown in the photo is a lithium ion battery pack that will be used to power the heaters on the powerlet. It fits nicely into the stock cutout. I've got a thermistor temperature controller on order that will also fit into the stock next to the battery pack. The controller will allow setting and maintaining the powerlet temperature within 1º F or better.

I'm finally able to hit what I'm aiming at without relying on a bench vise! The next step is to lengthen the barrel to somewhere between 16" and 20". This should make the gun quieter and produce higher muzzle energy.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on May 06, 2017, 06:32:44 PM
looks incredible./ I cannot wait to see some groups.. the muzzle velocity should skyrocket near 16 inches of barrel.I modded a crosman 1088 with a 9 inch barrel many years ago using a 1077 barrel section.. I doubled the FPE and went from 380fps to  525 .
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on May 08, 2017, 10:31:41 PM
The stock for the Vigilante carbine is moving right along. I was wondering how to deal with the awkward installing and uninstalling of the stock to change the powerlet. I finally decided to do some more milling and carving to make an opening for the powerlet to just drop in through one of the grips. It's still a crude affair, but the scheme works well. The stock can now be installed somewhat permanently with some recessed machine screws. I'll make a cover for the powerlet slot and secure it with a couple of small NIB magnets that will stick to the powerlet cylinder.

I had almost given up hope of ever being to shoot an airgun accurately, but this carbine design has turned the Vigilante into something special. It's like someone else is shooting the gun for me. If the new longer barrel project makes this gun even better I'll probably soil my pants!
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on May 13, 2017, 10:48:17 PM
There was a mention in the early days of this project that the powerlets could be heated in order to maintain a constant pressure in the power plant by controlling the temperature. Someone requested "now to find a way to make it portable". Well, here we are with the way!

The photo shows the Lithium-ion battery pack and the temperature controller as they will be installed in the stock. I'll make a mounting plate for these devices and do the simple wiring needed to power the heaters. This has turned out to be much easier than what I thought would be necessary when the original heaters were installed into the pistol frame and powered using a bench power supply.
Title: Re: Hacking the Crosman Vigilante
Post by: AmBraCol on May 13, 2017, 11:48:55 PM
And suddenly, firing a CO2 gun in the fall and winter becomes doable! 

Looking forward to seeing how this progresses.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on May 14, 2017, 01:00:29 AM
very cool..what wattage are the heateers
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on May 15, 2017, 03:20:05 PM
The heaters that I'm using are rated for 28 volts.  I use 2 of them and can run them in series or parallel using just 12 volts. This will produce either  5.5 or 11 watts for heating. The powerlet's steel case will act as a thermal flywheel for rapid firing. When I finish installing this heating arrangement I'll be able to plot out the powerlet's temperature vs number of shots vs time. This should be interesting.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on May 21, 2017, 04:43:54 PM
The powerlet heating system is working out well for keeping the CO2 pressure reasonably constant, but there is a practical ( and sensible) limit to how much heat should be applied. Once the powerplant is up to temperature at any given setting, it is the liquid phase of the propellant that is maintaining the pressure in the system. When the gun is fired the gas expands into the barrel and begins to rapidly cool itself and the barrel.

Since the barrel is already at a lower temperature than the heated powerlet, typically, it's a downhill temperature drop from there on. Now, if the barrel was heated to a higher temperature than the powerlet there could be some extra gain in pellet velocity. The heating could be substantially greater than that applied to the powerlet because the barrel is not under pressure except for the few milliseconds that the valve is open and the pellet remains in the barrel.

Using a second temperature controller and heater for the barrel would be easy. There is enough room for another controller board in the stock. The question now is how much heat can be transferred to the CO2 in the short time short time that its in the barrel. Any thoughts out there?
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on May 21, 2017, 04:50:59 PM
the barrel is quite vaguely connected to the valve and co2 cart, id guess bringing the valve up to temp would be more beneficial..
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on May 21, 2017, 05:16:43 PM
Actually, the barrel being thermally isolated from the pistol's frame is a good thing. The plastic barrel housing itself is a poor heat conductor and has some heat tolerance (to be determined). The barrel is therefor a good place to do the heating. If the valve was to be heated it would be a large heat sink because it is mounted directly against the metal frame. This would mean that the whole frame would attempt to come to some thermal equilibrium with the valve. That would be a very inefficient use of the battery and ultimately make the frame too hot to hold comfortably without gloves.   
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on May 21, 2017, 09:54:11 PM
Doing some preliminary testing for the barrel heating experiments It was instructive to measure the muzzle velocity of some pellets while the gun was back in the vise. With the powerlet temperature at ~ 80º F the first few shots were all well in excess of 600 fps. This was with the new 18" barrel. Within the same clip the velocity began to slowly drop to below 600 fps even with the powerlet temp being maintained. I found this to be a curious situation and waited a short time between shots to see if the velocity would come back up. It slowly crept back up a ways, but not to the initial numbers even thought the powerlet temp stayed the same. I then probed the inside of the barrel with a TC gauge and found that the temperature was several degrees lower than the room temperature. This must mean something!

This is only a simple observation and nothing quantitative, but I thought I'd offer it up for further speculation.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on May 21, 2017, 10:16:16 PM
very interesting , and the velocity is impressive.. thats higher than the average for a 1077 out of the box.. So, i guess these numbers will be a good baseline for comparison to the heated barrel
Title: Re: Hacking the Crosman Vigilante
Post by: dv8eod on May 22, 2017, 01:13:44 AM
Will you try heating the whole barrel or just a portion of it? It seems to me that the amount of heat needed to counteract the cooling effect from the gas would need to be quite high. Then there is the possibility of warping the barrel around the transfer port. You are rapidly chilling a hot piece of metal. It could lead to a split chamber, an oversize or undersized chamber, or a set bend or bulge. I'm not saying the effects would be immediate, but they are possible with chances getting better over time.
Then again, it's such a small metered amount of gas that is being used, there might not be any effect at all.

Something that might be going on; by heating the cartridge, you are increasing the amount of gas (from pressure) moving through the valve reducing the amount of liquid left in the cartridge. It might explain why it didn't recover to the previous speeds even after the break. The temperature in the barrel is interesting to say the least. I just can't imagine it being so cold as to hold the gas back from rapidly expanding.

As an aside, do you have a method to determine how many CCs are released each time the valve is opened? Something to compare shot to shot?
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on May 22, 2017, 04:44:07 PM
The barrel heating experiment is pretty straight forward. The heater will be the same type that is now being used on the powerlet. It will be attached on the breech end of the barrel. The temperature will be set to somewhere between 100º F to 150º F to start. There will be a temperature gradient down the length of the barrel toward the muzzle. This will be an easy bench setup.

As far as using direct measurement of volume as a metric for the test, it will be much easier and more accurate to get the numbers from the time/pressure curves.

On another note, I've been giving some thought to the area around the valve exit. There is no real seal between the detent cylinder and the cylinder plate. There is an ID/OD difference of ~.004". This could be a source of considerable(?) leakage when the valve opens. The plan at the moment for measuring this potential leak sight is to use the small probe attachment on a lab ultrasonic translator. I've got a vintage HP 4918A up in the attic somewhere that can can be pressed into service for this job. This instrument is very sensitive for finding small leaks in pressurized systems. Its directionality is also remarkable. Another use for this instrument is to locate the source and magnitude of friction. I had forgotten about the friction location capability. It will be interesting to survey the moving parts inside of the pistol frame. This could also be used with the pellet pushing experiments when I get back to them.

Anyhow, my for leak testing I'll measure the leak magnitude of the detent cylinder with the breech pressed against the cylinder's cone without having the pellet clip sitting between them. This will eliminate extra interfaces. The tests would be run with and without a pellet in the forcing cone. It looks like I'll be back on the test bench for a while.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on May 23, 2017, 10:53:12 PM
Here's a photo of the instrument and gun that will be used in the detent cylinder leakage testing. I'll also use the translator to evaluate the various potential points of friction in the cocking and firing mechanisms.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on May 27, 2017, 03:10:55 PM
While the bench testing is going on I thought I'd do a fit-test with a rifle scope on another build. I'm going to use this scope on the 18" carbine that's in the works.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on May 27, 2017, 09:59:10 PM
I did some target shooting at 33 ft. this afternoon using the new scope set-up and a rest. I didn't take any pictures, so the results didn't really happen!(?) When I get some photos, though, I think you'll find them impressive. The new 18" barrel and a new extended fore-stock should be ready by Monday.

This project has moved me far away from wanting anything to do with break barrel guns. The Benjamin Titian that I bought last year to deal with rodents has killed more scopes than rats! With my latest Vigilante carbine designs I'm ready for a new season of infestation in the trees and ivy. Bring it on!!
Title: Re: Hacking the Crosman Vigilante
Post by: sfcnewy on May 27, 2017, 10:02:53 PM
Very impressive from the start!!!
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on May 27, 2017, 10:12:18 PM
George,
I just found this great thread yesterday. I'm in awe at the breadth in expertise and equipment you've applied to help us understand airguns.
I'm also in awe that someone in Carlsbad has an attic.
Getting back to your latest experiments, It will be interesting to see if you can get any heat from the barrel into the CO2 in the short timeframe. The heat transfer coefficient may not be high enough. It would also be interesting to see if there is a change in the aimpoint as you heat the barrel. Since the sights attach to a plastic rail, this may drift with temperature. A laser pointer could help track that.

Thank you again for sharing with us the fun you are having with the Vigilante
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on May 28, 2017, 06:12:08 PM
I've been experimenting with various approaches to doing muzzle crowns. I've found that cutting and polishing compound facets seems to greatly reduce the number of fliers. Today I'm using a Temo 4mm green rubber burr to both cut and polish the facets. The Dremel motor is held in the tool holder and rotates at ~ 20,000 RPM while the lathe chuck turns at 1000 RPM. This keeps the facets concentric with the bore. The Dremel can be adjusted to any chosen angle. The facets are cut deeper than is customary. At this point it appears that the increased depth helps the knurled choke to be more effective. There's plenty of room for speculation at this point. I'll just put out the information as it accumulates.

The photos are of the 18" barrel that will be fitted into the next version of the Vigilante carbine. The results of various muzzle treatments will eventually be evaluated using schlieren photography when it gets its day on the test bench. The use of several short barrels with different muzzle treatments will be used for these tests.


Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on May 28, 2017, 09:50:32 PM
After giving the 18" barrel the new 'grind and polish' treatment it was tested out in the backyard range at 33 feet. The barrel housing of the gun was clamped in a vise and the sighting was done by looking down the bore to get a first approximation of where the center of the target was. I just wanted to keep things on the paper. The temperature was 70º F and no powerlet heating was done. A photo was taken this time to keep things real. What you see is the result of 8 Crosman Destroyer pellets fired in fairly rapid secession. There was no attempt to do anything quantitative in this test. It was the end of the day and I just wanted to shoot a few pellets at a target that was further away than the 15 foot range that I use in the garage. The group was so small in the garage that I had to check a couple of times to see if the clip actually had pellets in it!

All of this is testing the barrel before the choke is applied. Things are getting very interesting again unless some one points out that this is typical of the results from most Crosman 1077 rifles. Maybe it would be useful to buy a 1077 and do some testing on it. In the mean time I'll just gloat over the results.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on May 29, 2017, 02:56:23 AM
lol,I cant shoot that group with my 1077 at 5 feet.. but, thats the trigger.. the barrels could be really good for all I know.. very nice results.
Title: Re: Hacking the Crosman Vigilante
Post by: sfcnewy on May 29, 2017, 11:23:56 PM
Wow!! Everything in this thread is impressive! The research that you are doing is way beyond anything I have seen before. And on a Vigilante!!!
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on June 05, 2017, 07:31:51 PM
There is a lot of information about airgun pellet muzzle velocity out there. If the chronograph that you're using doesn't also give you the muzzle energy, it's an easy matter to plug the velocity into any of the calculators available on the internet and get an energy number if you know the pellet's mass.  What there seems to be little information about is the true pellet energy at the point of impact (POI). I've gotten temperately distracted with POI measurements lately and decided to set up an experiment to make those measurements.

Earlier, I had posted some info about using a force transducer as a timing marker to measure the transit time for a pellet in a barrel. This approach worked well and some good numbers were generated. Now it can be used for the job it was intended to do and it should make an excellent way to easily get POI numbers.

The original transducer was mounted on a block of aluminum and a PVC pipe end cap filled with duct seal is used as a trap for the pellet. That was an OK target when it was placed at the muzzle but I'm interested in making measurements at 5 to 10 yards now. This will require a larger target If I'm the one shooting at it! To that end I'm replacing the small PVC cap with an ABS one. It will also be filled with duct seal.

The measurements will start with the transducer at the exit of a Combro chronograph which is attached to the barrel. This will be ~ 4" from the muzzle. The Combro can output both velocity and energy. The output of the force transducer will go into a Kistler 5026 Dual Mode Differential Amplifier. The 5026 amp can then be calibrated to give an output signal that matches the Combro energy numbers. This output signal will go into the LeCroy scope where the pulse can be captured and stored. The scope can then calculate the energy/time integral between two cursors.

My interest in this experiment is to make sure that a pellet from my Vigilante carbine will be able to humanely dispatch rodents at 5 to 10 yards. This information may also be of interest to any spreadsheeters that might be watching........
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on June 05, 2017, 10:49:19 PM
Extra photo.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on June 09, 2017, 10:35:15 PM
The new force transducer/target stop combo is working very well. The ability to get the force/time integral now opens a new chapter in doing some of this bench testing. I'm going to go back to the pressure/time curves and investigate those experiments using the same type of analysis. There doesn't seem to be any end to this. I find that to be very satisfying.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on June 18, 2017, 10:24:27 PM
There has been some discussion from time to time about the sound levels of airguns. I've taken some steps in that direction, but keep retreating because of the ambiguity involved in making and interpreting the results. There is no standard method of doing the testing as far as my reading has been able to come up with. Therefore, I've continued to find other things to fritter away my time with on the test bench besides sound levels.

The typical quagmire involves variations in methods, instruments, distances, weighting factors, etc. The problem that I've found most perplexing is that virtually everyone who uses a sound level meter (SLM) to measure gun noise tends to just aim the SLM toward the barrel and assume that the numbers it gives you are real and valid. The easiest way to avoid wayward discussions about 'proper' SLM measurements is to not get involved.

Well, I've collected too much sound and vibration instrumentation over the years to abandon the measurements at this point. The only way out of the speculative arena of these tests is to design my own approach. This comes about because I was recently asked if, and how much, the barrel mods I've been doing change the noise level of the Vigilante. Embarrassed, I had to admit that I couldn't give a number, only an impression. I've decided to resolve the issue and try to redeem myself.

Here's what I'm going to do. First, I'll consider the that the only real number that relates to the gun's noise level is what exits at the muzzle. I'll further assume that this noise is an 'impulse'. Any other noise in the measurement is directly associated with the environment in which the measurement is taken. The environmental noise is always going to be unique to sets of reflections, time delays, and the instruments' responses to them. Let's also assume that I'm only interested in measurements made on MY guns using MY setup geometry and MY instruments. This will always give me reproducible results if nothing in the experiment changes. Now I can give reliable impulse numbers that relate directly to any changes in the barrel mods.

I'll expand on this as the measurements progress.


Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on June 23, 2017, 11:10:04 PM
The time has come to get some real numbers relating to how loud the Vigilante pistols are from the factory and and from the longer barrels that I've been working on. I've chosen from a collection of General Radio and Bruel & Kjaer instruments that I've been collecting over the years and have narrowed the preliminary test down to mostly the B&K devices. The GR instruments are also excellent, but when you have a choice it's hard to get past the overall exquisiteness of how B&K builds things.

Anyhow, What I've chosen to start with is a 1/4" laboratory microphone capsule type 4136 coupled to a type 2639 microphone preamplifier. These are run through a dual preamplifier power supply type 5935. The output of the 5935 is then routed to the input of a measuring amplifier type 2636. The 2636 processes and conditions the signal and then sends the output to the LeCroy scope for further evaluation.

Most of the measurements that I've used this equipment for has been audio testing and measurements for designing and building planar magnetic loudspeakers. Those were the days! Well, membrane speaker diaphragms are fast, but nothing compared to what I'm measuring now with pellet guns. I'm seeing things that are not intuitive and have clearly shown that good impulse measurements simply can't be done by any commercially available sound level meter. I though this was going to be easy, but I was quite wrong.

I'll proceed slowly in the following posts so that those of you still watching this thread may also be able to enjoy the very interesting (to me) things that are beginning to materialize from the tests. If you doze off, that's OK, too.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on June 28, 2017, 07:18:32 PM
Since I said that I'd start slowly, let's look at what the limitations are of the measurements. The photos show what a fast positive pulse from an HP 3310B Function Generator looks like. As can be seen the rise time on the pulse going straight into the scope's channel 1 is 40 nanoseconds. The channel 2 trace is what the 2636 measuring amplifier output looks like from the same signal. The rise time is 1.06 microseconds with some overshoot, but no ringing. This represents a bandwidth for the 2636 of over 300 KHz. B&K rates the bandwidth conservatively at 200 KHz. Most of the SLMs are rated at 20 KHz.

Next we'll deal the microphone and its preamp.
 


Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on June 28, 2017, 10:17:27 PM
An important part of making impulse measurements is to understand the way in which a Type 1 SLM  actually manipulates a very fast signal. It takes some amount of studying to get to the bottom of measurement standards, so I'll just take you on a shortcut here. A signal coming from the microphone is passed through a selection of various filters before the meter presents a value to be read. The filters are called "weighting" values. The most common weighting is "A". They are designed to allow the incoming signals to be contoured to the way our ears perceive sounds. These weighting filters are suitable for things that would be encountered in most everyday circumstances in the typical workplace.

The problem is that reports from gun muzzles and explosions are not usually part of the workplace environment (well, maybe not so uncommon now, but....). When the SLM is set to measure "impulse", for instance, the rise time and filters alter the signal to the point where the values read out are quite meaningless. As an example we can take the previous pulse signal that came through 2636 unmolested and switch in the identical weighting filters that a Type 1 SLM would use to represent the "bang". The photos show how the signals look as the SLM would represent them. I'll slowdown the time window so that we can see the full effect of the weighting. The traces are offset vertically for clarity.

The first photo is the pulse as seen in the last post.

The second photo is with an "A" weighting.

So, my question is, what are those people on YouTube really telling us about how loud a gun is when they use an SLM to measure it?


Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on June 29, 2017, 03:53:56 PM
The 1/4" microphone's preamp has been changed to a B&K 2633 type. The system's next addition will be a B&K Band Pass Filter Type 1617. This completes the requirements for a Type 0 sound level meter. It's time to start making some muzzle blast measurements. As stated before, the numbers that come out of this setup are going to be very reproducible, but unique to this testing arrangement. The initial measurements will be with the microphone placed 3" in front of the muzzle and 2" above the axis of the barrel.

Preliminary measurements indicate a sound pressure level of 152 dB. This is a big number, but well within the microphone's upper limit of 185 dB. The closest reflection surface has a time delay that is well outside of the time measurement window. The photo shows the basic arrangement for doing these starting tests.   
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on June 30, 2017, 11:39:51 PM
I finally got around to doing a couple of experiments to confirm that my time has been well spent putting together a hot rod impulse measuring system. This first set of experiments is definitely ground breaking info (to me) about airguns , but may seem ho-hum to others with more experience in these matters.

I've been doing a lot of reading of late about the best ways to do impulse measurements on firearms. This arena is where the real testing quagmire is getting sorted out. There is starting to be some agreement as to how the testing should be done. There is basically nothing of interest that I've found that relates to airgun impulse measurements. I won't belabor the subject here, but I would like to share some stuff I've captured with the new instrument setup.

The photo shows three different shots. I'll try to keep this simple. The top trace is channel 1 and represents a typical pellet shot in a 1 mS time window. This same time window is used for all three shots. The first pulse starts and finishes in about 50 microseconds. In firearm parlance it's called the 'N' wave. Keep in mind that the display of these pulses is inverted. Don't worry about that for now.

From everything that I've read so far, the N wave is the air in the barrel being compressed into a supersonic shock wave by the advancing bullet traveling up the barrel in excess of Mach 1. There is always a time interval between the clear N wave and the start of the 'real'(?) muzzle blast. Since the N wave is of the same magnitude as the blast coming from behind the projectile, what do you think the ear does with the first shock wave? Ignore it? If we use A weighted impulse measurements then, yes, it is ignored by the METER!. That's enough for now on the top trace.

The second trace, in the middle, is a shot with some canned spray duster sprayed into the barrel just before the shot. The duster gas is about 2.2 times as dense as air. It was sprayed in to displace most of the air in the barrel.

The third shot is a quick followup after the middle shot to see how much of the duster gas was removed from the barrel. There's something interesting going on here that I'll just throw out there for speculation. Keep in mind that we're only looking at 1 mS of information.

This looks like the entrance to another rabbit hole.

 
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on July 01, 2017, 02:25:31 AM
George,
Did you ever set up the high speed microflash unit you showed us in Jan? Could that be triggered by or at least synchronized to the audio signal and show the pellet position compared to the audio time trace?

Also, is the baseline (trace 1) relatively repeatable?

This is all great reading. Thank you
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 01, 2017, 06:47:30 PM
High speed photography is moving up the list of experiments. Being a free spirit has its drawbacks. My attention span controls what I end up doing each day. Having several things going at the same time is OK with me, but it drives my wife nuts. And then there's the beer.....

As for the repeatability of the displayed impulse waveforms, they show everything exactly as the microphone sees (hears?) them. If the setup isn't changed the only difference in the display is a difference in what leaves the muzzle.

It might be helpful to examine the top waveform in the last post. What we see is the N wave of the air that was compress between the muzzle and and the breech as the pellet enters the forcing cone. The arrow at the bottom of the grid indicates exactly where the trigger starts to record the event. Each vertical line of the grid is .1 mS (100 microseconds) apart. The space to the left of the arrow shows what happened .1 mS before the waveform trigger said 'go'. There is essentially no ringing behind the N wave.

~ .22 mS behind the N wave the pellet leaves the muzzle and the CO2 blast emerges along with a series of well defined pulses. I'm going to assume that these pulses are the same ones that showed up when the pressure/time waveforms were recorded. I think I'll change barrels and remeasure the p/t curves with the microphone and pressure transducer running simultaneously.

The second (middle) trace is interesting because it indicates that some air reentered after the duster gas was blown into the barrel and before the pistol was fired. The small first pulse is the compressed air followed by the larger peak caused by the compressed duster gas followed by a series of smaller pulses. The duster gas is heavy, which makes it slow to compress and that the speed of sound in the gas will be slower. Are these smaller pulses shock waves or standing waves? What's also of interest to me is that the air and duster gas didn't mix. they both have distinct and well defined peaks. The barrel appears to be acting like large diameter capillary column as used in gas chromatography separations. This needs further investigation.

Since all three traces are triggered by the air N wave, the time delay and shape of the pellet's muzzle blast have a lot of information content in just 0.9 milliseconds of recording.

What's happening in the third (bottom) trace should be clearer now, so I'll leave it as a pop quiz!
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 02, 2017, 07:41:21 PM
As an aid to understanding what's going on in the previous scope traces I thought it might be helpful to convert the screen grid into distance instead of time. I'm confident that most of you following this thread can switch between the time and distance relationship in your heads, but there may be some that don't have that faculty. Therefore, I'll post the scope display photo again (now that we're on a new page) and state the time vs distance conversion.

The speed of sound in air at 74º F (when the test was done) is 1132.17 f/s. That's the same as 13,586 in/s. Now, if we convert the display time interval for each vertical line increment into distance traveled by just the air N wave in trace 1 we will get 1.356" or ~ 1-5/16". That makes the distance between each dot 1/5th of the distance between vertical lines equal to .272" or a little over 1/4". That put's the pellet's instantaneous position as it leaves the muzzle at ~ 3" behind the N wave .

I know all of this has a big "so what?" factor attached to it, but this really helps me to do things like set up the high speed shadowgraph experiments.

Again, I'd like to thank all of you who are following my musings and allowing this thread to continue into the unknown.
Title: Re: Hacking the Crosman Vigilante
Post by: dv8eod on July 02, 2017, 08:04:55 PM
You don't have to thank us, just tell us who is going to publish all your findings into an encyclopedia for airguns.  ;) ;D
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on July 02, 2017, 08:54:18 PM
George,
I was thinking the position lag of the pellet would be based on pellet velocity (~500 ft/s?) not the speed of sound. So for the .22ms this would be around 1.3". That leads me down the rabbit hole of what pellet velocity does it take to form the N wave?....did I go down the wrong rabbit hole?

Thanks for data and insight
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 02, 2017, 10:56:49 PM
Stan - I think that the N wave is probably new to everyone as far as airgun measurements go. I'm not sure (yet) what the pellet velocity in the barrel needs to be to produce a sharp N wave. My excursion into time vs distance conversions is only to determine where to place the microphone to capture the best muzzle images for the shadowgraphs. I didn't even know that the N wave existed at these low velocities. It's a boon to my thinking and very useful for things down the road. These experiments will continue and I'll report my findings for others to consider.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 03, 2017, 04:47:46 PM
I've been doing some research on N waves. As was previously asked, it would be interesting to know how fast the pellet would have to be going to produce them. The closest that I've come to what's going on in an airgun barrel is in references about "open-end shock tubes". These most closely resemble a gun barrel. Many of these devices are driven by compressed air. Apparently these waves are common in many everyday events like hand claps and popping balloons. The wave doesn't have to be supersonic, just loud enough to form a strong pressure wave. This requirement would allow the pressure wave to remain at Mach 1 at the muzzle and beyond.

I've looked at some high speed shadowgraphs of everyday events and the claim is that the sound pressure level for good images needs to be on the order of 110-120 dB to get enough contrast. This would explain why the scope trace N waves we're seeing near the airgun muzzle are so clear and prominent. The microphone in these experiments is recording ~150 dB at its position. I don't know yet how slowly the pellet would have to be going down the barrel to not produce an N wave.

This gets us back to the pellets velocity relative to the N wave being generated. This wave will always be propagating at Mach 1 in CO2 powered guns. That info is a very useful tool to have.

If I've missed something here please let me know.
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on July 03, 2017, 06:57:54 PM
I found an interesting comparison of .22 starter pistol shooting blanks and bullet rounds. In that short barrel pistol it should be subsonic, though faster than the pellet.
http://c.ymcdn.com/sites/www.hearingconservation.org/resource/resmgr/imported/Sondergaard_Jacob_022511.pdf (http://c.ymcdn.com/sites/www.hearingconservation.org/resource/resmgr/imported/Sondergaard_Jacob_022511.pdf)

Here they added a .32 pistol

http://c.ymcdn.com/sites/www.hearingconservation.org/resource/resmgr/imported/Soendergaard_Jacob_022512.pdf (http://c.ymcdn.com/sites/www.hearingconservation.org/resource/resmgr/imported/Soendergaard_Jacob_022512.pdf)

The same group described their instrumentation and methodology here for a high velocity rifle. I would guess they used something similar for the pistol tests.
http://www.sandv.com/downloads/0908rasm.pdf (http://www.sandv.com/downloads/0908rasm.pdf)

Kind of fun trying to diagnose the results

Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 03, 2017, 09:31:31 PM
Thank you for posting these resources. I've read them earlier and it's where I became aware of N waves. There is also a good deal of info from US military testing and NATO. The problem I'm having now is to try and relate these published findings with what the airgun signals look like. With airguns, in general, there is no extreme barrel pressure and high temperature to contend with. This make the airgun measurements easier and less complicated, but there's still a lot of speculation, interpretation, and understanding that's left to do. That's where the beer comes in!
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 05, 2017, 08:17:37 PM
To add to the confusion I found this information today.

Acoustical Characterization of Gunshots   Robert C. Maher Department of Electrical and Computer Engineering Montana State University Bozeman, MT

"A subsonic rifle or handgun without a suppressor will produce a muzzle blast acoustic signal, but the subsonic projectile will not create a shock wave or any other appreciable acoustic signal as it propagates through the air."

What's wrong with this picture?

After doing a lot more reading and attempting to get a better understanding of acoustic measurements relating to airguns a clearer picture is beginning to form. I'll have to admit that I misinterpreted the above statement about shock waves. After parsing the sentence I realized that I didn't pay attention to the part about "as it propagates through the air." I was still thinking about the impulse wave generated by a subsonic pellet "propagating through the barrel". So, it is true that a subsonic projectile won't produce an "appreciable acoustic signal" on its own.


Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on July 05, 2017, 10:11:03 PM
In the picture of your test (6/29), it looks like the pistol and the microphone share the same support stand. Is there any chance that there is a coupling through the supports?
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 05, 2017, 11:12:32 PM
Yes, there is definitely coupling between the two, but that would show up as a ringing like a damped tuning fork.  Also the time window for the measurement is too short for the ringing to effect the measurement.

I did the test anyway just to make sure that nothing was overlook in that area. The test was done by using the same settings that the original measurements were made with and just tapped the stand and gun with a small hammer. Even with some aggressive blows (far more coupling than the muzzle blast could impart) I couldn't get the system to even trigger the scope.
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on July 06, 2017, 12:23:14 AM
Thanks for checking that. I thought maybe the initial hammer strike was registering. But you are right there are enough joints in that support path to quickly attenuate that.
For a shot without a pellet would there be just the muzzle blast signature since there is nothing to generate the N-wave?

I did find a few more papers  by Maher from around the same time frame...Looked like they used the same data.

Another paper showed a .45 cal handgun (presumably subsonic) response that had a leading N-wave
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 06, 2017, 03:42:23 PM
Here's a quick test that was done this morning. The photo shows the top trace of a shot with a pellet in the barrel. The bottom trace is without a pellet in the barrel. As can be seen there's a marked difference in the amplitude of the two traces. The top trace is set to 1 volt/division. The bottom trace is at .5 volts/division. The muzzle N wave with no pellet is still distinct, but the CO2 has changed shape and is moving faster because it isn't pushing a pellet. There is still a time lag with the CO2 which indicates that the air in the barrel is acting like a plug of gas. This sort of effect is very apparent in the duster gas experiment shown in an earlier post.


Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 07, 2017, 10:42:56 PM
Now that we know that the N wave exists in even low velocity airguns and is easily recorded, it would be nice to know what the frequency content of a muzzle blast looks like. I've searched for any information about the airgun spectrum, but have found nothing of interest yet. There is some info about small firearm spectral plots, but they aren't in good agreement with each other, so it looks like another can of worms to sort through.

Rather than rely on what has been published for firearms it would make sense at this point to just do the measurements and get the truly relevant numbers for our airguns. The LeCroy scope has an FFT mode that can easily do the job, but I've also got an HP 35665A Dynamic Signal Analyzer sitting in the corner that's not earning it's keep. It's a fine instrument that's enjoyable to work with and may be up to the task.

I'm starting to think that when the dust settles there will be more than just measurements of the differences between Vigilante barrel upgrade noise (the original reason for doing these tests). It may be possible to design a barrel housing with a new type of Impulse damping. 
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 08, 2017, 09:23:13 PM
Now that the experiments are going in the direction of making frequency spectrum N wave and muzzle blast measurements it's going to require a standard mechanical impulse generator. Rather than using the gun itself for these test I've decided to build a simple device to at least make N waves. If this works I'll be able to do the first tests many times without having to use up powerlets and pellets. The device is also more compact than the pistol arrangement.

As the photo shows, it was a simple task to re-purpose a mousetrap into a new laboratory instrument (the proverbial better mousetrap). The snap is loud and will probably make useful N waves. We'll see.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 09, 2017, 05:45:27 PM
This mousetrap snapper is looking very interesting as a noise source for doing impulse testing. At 1 foot from the microphone the sound level is reproducible at 137dB +/- ~ 1 dB.

As can be seen in the photos the time to peak is 9.5 µS and the ramp back down to the baseline is 16 µS. That's not bad for such a simple contraption. Also, one of the hallmarks of an N wave is a fast rise and a slower ramp down. Now, I'm not going to say that this first pulse is 'for sure' an N wave, so that leaves room for the rest of you to reassign it as something else. In the mean time I'll just claim the device to be a good reference for something loud and fast.

The third photo shows the full impulse decay envelope when the scope is slowed down. It looks pretty classical to me.
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on July 09, 2017, 10:33:46 PM
Love the impulse standard.

When you mentioned getting the frequency content of the response, how would the result be evaluated?
I don't have an acoustics background so some web search helped.
For continuous tones, the the equal-loudness contours are used https://en.wikipedia.org/wiki/Equal-loudness_contour (https://en.wikipedia.org/wiki/Equal-loudness_contour) but these don't apply to an impulse.

For short duration (<200ms), there is a significant reduction based on the response time of the ear. http://cjur.ca/wp-content/uploads/2017/03/Identifying-Perceived-Loudness-in-Audio-Signals.pdf (http://cjur.ca/wp-content/uploads/2017/03/Identifying-Perceived-Loudness-in-Audio-Signals.pdf)

I suspect the answer is also different if one is interested in detection or in damage.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 10, 2017, 04:16:07 PM
As a reminder to myself I'll comment that the purpose of these impulse measurements is to test the different loudness levels of the various Vigilante barrel modifications. Under normal circumstances hearing loss wouldn't be a consideration unless you were to get shot through the ear. I'm talking about typical CO2 guns, of course.

Most often shooters are actually concerned about airgun noise leaking over into the neighbor's property. A quieter gun would also be desirable for target practice indoors. Rather than sticking with just comparative levels of attenuation with barrel length, it now seems to me that all of these impulse experiments might steer things toward quieting techniques that can be incorporated into whole barrel assemblies.

My propensity to stray far from the original course is what's driving this latest boondoggle. I think that some good information can be squeezed out of all this testing and that some other folks might benefit from it, too. I have to confess that I'm learning a lot more than I had anticipated.

Evaluation of the results is up to what one chooses to take away from all this. I'm writing my own standards for in-house use as comparisons on my own projects.

It's all here for the taking.
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on July 11, 2017, 05:00:21 PM
Yep, at my age, additional hearing damage from airguns may be a low risk...and I hope shooting my self in the ear is as well (though the foot is often at risk)

For kids though, the exposure thresholds are lower (120db per WHO) so some consideration may be appropriate.

Data for different airguns here https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4896309/ (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4896309/) I was surprised that there wasn't a big difference between the lead and alloy pellets. I would expect the alloy to be supersonic. Their instrumentation (1/2" mic) may not be good enough to catch the peak.

Also shows the comparison of muzzle plane and ear location mic response. would have been nice if they had a time domain response chart.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 11, 2017, 09:18:18 PM
Thanks for the new reference article. I'm adding it to my expanding list of information that is now flowing into a growing pool of uncertainty. It's all grist for the mill.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 12, 2017, 07:04:46 PM
I've gone back to doing some bench shooting in the garage. I have three pistol frames that can be switched between different barrels for testing. I noticed that 2 of the frames came from the factory without any lube. The one with some lube had just a swipe of grease over a couple of parts and it was obvious that it had been applied after the gun had been assembled. A friend took his Vigilante apart and found that it had no lube at all, either. My choice for doing a lube job at all of the sites that needed it was to use a drop of type 68 way lube oil that I use on the lathe and mill. The "tackifiers" in the oil help to keep it from migrating away from where it's applied and also has other interesting properties.

One of the frames had been disassembled and was laying in pieces on the bench for a while now. This is the one that I mentioned had a gap between the cylinder plate and detent cylinder. BTW, they all do. While I was considering how to close the gap (~.004") I got distracted with some other measurements. Today I decided to just put the gun back together without any mods and see if there was much difference between a couple of different frames on the same 10" barrel. It was surprising to find that there was a significant fps reduction in the newly assembled gun compared to one that was used quite a bit. This required some head scratching.

After a couple of beers to clear my thoughts I tried looking through the side of the pistol and watching the clip as it was rotated by hand. There were points when the detent cylinder didn't sit squarely into the pellet clip detent. This caused a gap to form on the other side of the clip between it and the breech of the barrel. The frame was disconnected from the barrel and the detent cylinder was then accessible for poking at. Using a pencil, I could rotate and tilt it some. There were points were the cylinder would get stuck and resisted rotation. After applying a drop of Pellgunoil to the recalcitrant part things worked much better.

The frame was put back into service on the same barrel and the improvement in fps was remarkable. Sometimes it only takes a drop of oil in the right place. The improvement may also have been enhanced by the oil having sealed the .004" gap that was spoken of earlier.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 14, 2017, 03:30:57 PM
I've been thinking about the acoustical measurements that have been posted lately. It seems that I've been getting myself, and possibly others, confused by trying to use crossover terminology and definitions. If one evaluates the properties of a classical N wave produced by a shock cone from a supersonic projectile you'll see a fairly symmetrical trace that indeed looks like the letter N.

The traces from the microphone that are recorded in my experiments are pre-muzzle blast impulse records, but they aren't shock waves from a supersonic source. They are compressed air (or other gas) events that precede the pellet exiting the muzzle. They are shock waves none the less.

To avoid any conflict with firearm nomenclature I'll refer to them, for the time being, as just impulse (Imp) waves when they come from subsonic projectiles leaving an airgun barrel or the new impulse generator. As stated in an earlier post, shock waves can also come from many common subsonic sources.  I don't know if this helps or hinders the cause, so if any of you have a other ideas about this I'd like to hear them.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 14, 2017, 08:27:56 PM
Stan - Thanks for the missive.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 17, 2017, 07:03:00 PM
Now that I'm re-acquainting myself with the HP Digital Signal Analyzer (DSA) it's clear that a person can get more information out of these instruments than can be easily digested. The ability to do wideband testing with high resolution is starting to remind me about not being able to see the forest because all of the trees are in the way!

I've decided that the information I'm looking for can best be represented by using fractional octave analysis. This type of measurement represents acoustical energy in a way similar to how the ear and brain process sounds. It's an old method and not without is foibles, but for what I'm after it works well. The impulse nature of this noise is also problematic, but if we discard the notion of potential hearing damage, things are again simplified. I'm going to limit the bandwidth to between 20 Hz and 20 KHz. This is plenty for the testing that I want to do because I'm only interested, at the moment, in evaluating perceived loudness.

The impulse standard I've built has a definite tendency to disproportionately produce higher frequencies. I'll try to redistribute the spectrum by tuning the striker board. This in itself looks like an interesting project.

Where's all this headed? I have no idea!
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on July 17, 2017, 11:22:08 PM
So, letting Google take me past the weeds, into the rabbit hole and into the weeds in the rabbit hole, I find papers such as http://boson.physics.sc.edu/~kunchur//temporal.pdf (http://boson.physics.sc.edu/~kunchur//temporal.pdf) which looked at temporal resolution in hearing. An interesting quote: "In one experiment by Leshowitz (1971), listeners were presented with a single pulse or two narrower pulses (with the same total energy) separated by an interval Δt. The click and click-pair could be distinguished down to Δt ≈ 10 μs" Other times were observed for other sound types, but it seems to bound the ear's response time. Gap detection in noise was much slower at 2 ms. Your nominal .22 ms result for the two observed shot peaks is in that range so in my mind, the question remains whether it is the amplitude of the two individual peaks or the combined energy that drives the perceived loudness.

Lots of hits under the topic of temporal summation of loudness

One more beer before I push search again
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 19, 2017, 03:20:19 PM
I agree that there are many paths to explored when it comes to evaluating sound, noise, and impulse signals. The path I'll take at the moment is a pragmatic one. This divergence into acoustics is, at the moment, only to be able to give a reasonable answer to the question about the sound level difference between the factory 6" barrel and the 10" upgraded barrel. I'll make the same comparison using the new 18" barrel.

I can always revisit these measurements when they can provide information about other aspects of impulses. I'm still very interested in alternative methods of attenuating muzzle noise.
Title: Re: Hacking the Crosman Vigilante
Post by: Tomg on July 30, 2017, 11:26:34 AM
George, this is massively interresting, you are doing and finding the same issues I have found on sound level testing. In case you are unaware, there are a milspec (actually a couple) standards for testing impulse noise from guns. It requires a 20microsec rise time capable device such as tge B&K or the Larson & Davis LTX. I got one of the latter and have their 90 to 190db micon it. After many hours of living inside the manual and its user interface I know how to use it. To my suprise ag impulse levels are much louder than I expected. The milspec standard I have employed is 160cm above ground, 100cm distance to the muzzle at 90 degrees and 10m away from reflective surfaces (walls etc). Since my mic dont allow for anything less than 90db I have placed it at 50cm distance from the muzzle which is half distance which increase the spl by 6db. So its a simple method to take readings and deduct 6db from the result.
My device can messure both impulse and averages at the same time. Infact it does 2 averages one being an average over a fairly fast cycle and one at the typical average. The other thing it let you do which is immensly helpful is that it can use different weighting for the different messures. So for impulse i can use linear (no weight) and a or c weighting for the others.
Anyway, not hijacking your thread, just filling in with more knowledge.
Title: Re: Hacking the Crosman Vigilante
Post by: Tomg on July 30, 2017, 01:26:14 PM
Sorry...my phone double posted
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 30, 2017, 05:54:42 PM
It's good to know that others are trying to make measurements on airgun loudness levels. Larson Davis makes some fine SLMs.

Also, you're not hijacking the thread, you're adding information.

I am aware of the various attempts to standardize the measurement methods by various agencies and organizations around the world. None of these efforts are directed towards airguns as far as I'm aware of. Some interesting links have been provided in previous posts in this thread. All relate to firearms.

A few things to keep in mind while trying to make sense of all this info include the chain of events that go along with the final numbers. It's important to know the rise and decay times of the microphone, preamplifier, filters, and measuring amplifier. The best and most reliable method to evaluate the total system performance is to capture the system's output signal on a storage type oscilloscope. Without well defined timing and amplitude information it's difficult to know where the numbers are really coming from and where any bottlenecks are. A type 1 SLM has builtin constraints in order to conform to agreed upon specifications and tolerances.

A simple example and case in point is the type 1 SLM's Impulse response time window. The standard requirement is that the window be 35 mS wide. Now, to a first approximation sound at 70º F will travel 1.13 ft/mS. This distance times 35 mS is about 40 ft. That means that any reflection less than 20 feet away can become part of the measurement. The amplitude will be diminished, of course, but consider the ground (grass, dirt, concrete, blacktop, etc.?) being only about 5 feet away in a typical measurement geometry. How far away is the shooter from the microphone? All of these reflections are integrated within the impulse window.

There are other settings that can be used on some SLMs to look at impulses, but without a fast stored image on a scope it's still guess work.



Title: Re: Hacking the Crosman Vigilante
Post by: Tomg on July 31, 2017, 03:34:31 PM
35 micro seconds is a cycle lasting only 0.000035, so I doubt the reflections any closer than 1m would affect the impulse reading (peak). The Larson & Davis have a cycle time of 25 micro sec.
However if any averages are taken in the millisec range could be colored by reflections if they are sufficiently close.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 31, 2017, 04:30:50 PM
For clarity I'd like to bring the time units into perspective.

1 µS = 1 microsecond = 1/1,000,000 of a second = 0.000001 seconds.

1 mS = 1 millisecond = 1/1,000 of a second = 0.001 seconds.

Type 1 SLM specifications require an Impulse time window to be 35 mS which is equal to 35/1,000 of a second (0.035 seconds.)

I hope this information is useful.
Title: Re: Hacking the Crosman Vigilante
Post by: Tomg on July 31, 2017, 04:47:36 PM
For clarity I'd like to bring the time units into perspective.

1 µS = 1 microsecond = 1/1,000,000 of a second = 0.000001 seconds.

1 mS = 1 millisecond = 1/1,000 of a second = 0.001 seconds.

Type 1 SLM specifications require an Impulse time window to be 35 mS which is equal to 35/1,000 of a second (0.035 seconds.)

I hope this information is useful.

Very good George, most over the counter db meters are in the mS range, which absolutely will be picking up some reflections. Most of them are not doing peaks either, only averages over said range.
When you step into the µS space, you start paying for your equipment by a huge margin. I am trying to take mine and doing some testing across a wide array of AG with the help of a fellow AG fan.
I've have so far tested break barrels, .22 and .177, gas/nitro piston break barrels .22 & .177. PCP's .22 & .25. The peaks using the milspec standard netted 148db peak impulse, and 120.2db avg over 0.025sec on a short barrel 38fpe gun with some hammer bounce.

Ps. The current milspec standard for gun/explosion impulse metering is 25 µS, A-weighting.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 31, 2017, 08:39:01 PM
The quest for better measurements using a type 1 SLM is still evolving. I found a copy of the MIL-STD here:  http://everyspec.com/MIL-STD/MIL-STD-1400-1499/MIL-STD-1474E_52224/ (http://everyspec.com/MIL-STD/MIL-STD-1400-1499/MIL-STD-1474E_52224/)

It appears to be the latest version. It looks as though the bar has been raised again. The 10 µs requirement is making things more interesting.

What I'd like to point out is that the meter specification calls for a 'peak' measurement which is different than the type 1 'impulse' measurement.

MIL-STD-1474E   15 April 2015   SUPERSEDING    MIL-STD-1474D 12 February 1997

4.7.4.3   Peak sound pressure level measurements.  The peak sound pressure level measurements shall be made using either a peak reading sound level meter or a combination of instruments with equivalent characteristics, such as a sound level meter and an impact meter, or a sound level meter and a calibrated oscilloscope or other appropriate calibrated display instrumentation.  The measurements shall be made with a sound level meter capable of making peak sound pressure level measurements with the total rise time of the instrumentation not exceeding 200 microseconds (µs).  The rise time of the peak detector shall be such that a single pulse of 200 µs duration produces a meter indication within 2 dB of the indication produced by a pulse having a duration of 10 µs and equal peak amplitude.  The amplitude of the 10 µs reference pulse shall be such as to produce a meter deflection 1 dB below full scale.


The requirement of  "The amplitude of the 10 µs reference pulse shall be such as to produce a meter deflection 1 dB below full scale" places a real demand on the crest factor for any SLM.

Fortunately, I'm only interested in making up my own rules for the relative loudness of airguns while using a type 0 measuring system.
Title: Re: Hacking the Crosman Vigilante
Post by: Tomg on July 31, 2017, 08:45:10 PM
Yes, they are also looking at changing the location of the measurement to be close to the shooters ear. I think it was 12" from mic to earlobe.
But at any rate, it's good to know what the standards are so that when you want to compare apples to apples, you can.
I should clarify, it's highly useful when you are trying to make sense of how efficient a sound moderator/technology is vs. another...which I am.

Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on July 31, 2017, 09:58:51 PM
I don't think that a comparison of firearm measurements to airgun measurements could possibly be an "apples to apples" situation. They each release their muzzle energy in different ways. If you're going to make devices for just airguns it might be better to compare device 'A' to device 'B' and then compare both to no device at all. This can all be done in your own dedicated and well thought out testing environment. If everything is fixtured and standardized for one specific measurement your numbers will only relate to any difference between the devices.

At that point you'll know if your making progress or not. No measurements in other venues with different guns, devices, or measuring equipment operated by other people can add anything but confusion. Stick with what you can control.

This is only the beer talking. Choose your own path.
Title: Re: Hacking the Crosman Vigilante
Post by: Tomg on August 01, 2017, 01:12:35 AM
George, 
You might have misunderstood my intention.
I am not suggesting comparing a firearm against a Airgun energy wise.
But the milspec standard is to meter the SPL (Sound Pressure Levels) And it's a log scale, so while we can debate the total energy output of them is not apples to apples, we can surely agree that let's say 130db at 1m at 90 degrees, is 130db at 1m @ 90 degrees regardless of the sound source as long as they are metered the same.

The reason why this is important is that when let's say you got brand X silencer for brand Y airgun and it reduce the DB level by 25db on airgun Y, you can now compare brand Z silencer and see how it compares to X.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on August 02, 2017, 10:26:25 PM
Now that I've chosen my path for making loudness measurements relating to the difference between the 6", 10", and 18" Vigilante barrel modifications, it's time to actually build the 18" model. I've been working on the design features that I wanted to Incorporated into this new carbine. I bought some parts from Crosman and started to do the machining to rough out the overall details.

Previously, I had been machining the rails for mounting a scope onto the barrel. This was time consuming and the part sill had to be painted or anodized. I finally came to my senses and looked for a weaver rail on the internet. UTG makes a nice one that fits perfectly onto the barrel housing rail and can be screwed in.

The photo shows the parts as they now are and the final machining and fit testing can begin. I'm sure that this effort will result in the best preforming gun yet.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on August 03, 2017, 02:12:37 AM
I'm sure the muzzle velocity will skyrocket.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on August 05, 2017, 03:51:58 PM
My curiosity got the best of me today so I decided to see how much each of the Vigilantes weighs. The scale was calibrated with a 5# Toledo weight. I was surprised at how light the 18" carbine build will be when it's assembled. A powerlet was in each pistol frame.


Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on August 21, 2017, 07:58:32 PM
I've been reading a lot about muzzle crowns lately. Almost everything that is out there refers to firearm muzzles. There seems to be considerable disagreement about whether or not the accuracy of any firearm is really improved using various crown and chamfer treatments.

There are some odds and ends written concerning the efficacy of these treatments as they apply to airguns, but they're few and far between. Some of the earlier tests that I've done on the Vigilante barrels leads me to believe that there can be a marked improvement in accuracy if the factory muzzle is re-machined and carefully crowned and chamfered. I attribute this fairly consistent improvement to the ballistic differences between pellets and bullets as they leave the muzzle.

Rather than start an opinion war here, I'll set up a few experiments that will demonstrate some interesting things that can be tested and measured using just the straw barrels from the Vigilantes I've been working on. I encourage those with contrary ideas about the experiments and their results to please step forward if I'm missing anything.

The first photo is of a Vigilante barrel as it comes from the factory. The second photo is of a barrel that has been given the lathe and Dremel treatment described in an earlier post.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on August 21, 2017, 10:32:46 PM
awesome job !
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on September 01, 2017, 09:40:58 PM
After looking at some more pushed pellets using a different type of microscope and revisiting the earlier micro-photographs of barrel cross sections I've come to see the potential value of barrel lapping as described previously by Scot Laughlin (classicalgas). I'm not a full convert yet, but I am willing to rearrange my thinking when I see new and useful information come out of my wandering experiments.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on September 03, 2017, 11:12:24 PM
It was an awakening for me to spend an evening using the stereo inspection microscope to view the pellets that I've been using . I've been too focused (pun) on all aspects of barrel treatments and have spent little or no time considering pellets. After looking closely at a collection of Crosman pellets that I've been using it became very clear that I've hit a wall as far as grouping performance is concerned. The closer look showed the horror of my situation. I may have made improvements in the barrels I'm working with, but any more improvements won't be demonstrable with cheap pellets.

I finally broke down and bought an array of RWS wadcutter pellets and discovered that there's a whole new world out there. I'll readily confess that it's a tyro's mistake to use garden variety pellets when you're new to airguns. I'm now reformed. I'll begin marching forward using only time proven superior pellets to up my game here. There is new hope for further improvements using a $50 Vigilante as the foundation for constructing the custom carbine that I've been fantasizing about.

I also realize that nothing really heroic is going to come from all of my experimental adventures, but in the end I'll have a nifty lightweight carbine that will serve me well in short distance shooting at targets and vermin. I'll also have learned far more about CO2 pellet guns than I thought I would at the start of all this. The journey continues.

More to come!
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on September 06, 2017, 05:53:32 PM
After showing my neighbor the first Vigilante I bought last year he decided to get one. I was over at his house this weekend and we did some target shooting in his back yard. We both noticed that his pistol was acting unusual so we started to inspect it up close. One of the first things that we noticed was that the pellet clip, when rotated, didn't make the usual clicking sound as the detent cylinder passed over the pellet holes in the clip. A closer look from the side of the pistol, when held up to the light, showed that the clip had to move further forward to engage the breech of the barrel then when it was new.

It turned out that the barrel was pushed forward enough to almost disengage the detent cylinder from the clip when the pistol was fired. That accounted for the loss of power and the obvious excess of CO2 leaking out from the sides of the gun. When the barrel was removed and inspected it could be seen that the shoulder at the muzzle end was not square to the barrel. The factory machining was poor, as expected, and it was clear that the cutting tool used was not set properly to the work. The effect was to have a wedge shaped shoulder pressing against the barrel stop at the end of the barrel housing.

Since I've made new and longer barrels for my Vigilantes the barrel stop is no longer part of the housing. I had not anticipated that this could be a problem down the road for a well used and unaltered pistol. To see if his gun was an anomaly I decided to inspect the 3 original factory barrels that were collecting on the bench. The photos clearly show that all 3 of them have tapers cut into the barrel at the shoulder. After some period of use the taper will deform the plastic. Eventually this insidious problem of the barrel moving forward will show up, to a more or less extent, in all of these guns that are tapered.

If you're a Vigilante owner it would be worthwhile to inspect your gun for barrel creep.


Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on September 09, 2017, 11:00:49 PM
Maybe most Vigilante owners know this already, but It bears repeating for those who might not. I've discovered that a double ended Q-Tip can be encouraged to fit into a .177 barrel with the help of a kabob stick or the like and then fired through with the gun's powerplant. Aim it into a waste basket or some other safe catching arrangement. They come out very fast. It's easy to see the cleaning effect when you inspect the two tips.
Title: Re: Hacking the Crosman Vigilante
Post by: AmBraCol on September 09, 2017, 11:08:56 PM
I usually snip the q-tip and just use one end at a time.  A couple drops of appropriate cleaner and through the barrel it goes.  The next few go dry.  Works great.  Don't have a Vigilante, but have used this method in various of my .177 caliber guns.

Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on September 15, 2017, 05:33:08 PM
The new weaver rail needed to be fit tested, so I put together another 10" barrel gun to see how it would look along with the new housing extension.  This housing is designed to protect the crown if the gun is dropped or bumped. I like it better than the exposed muzzle on the earlier builds.
Title: Re: Hacking the Crosman Vigilante
Post by: AmBraCol on September 15, 2017, 05:54:44 PM
Does this housing put the barrel under tension (like the old powder burning Dan Wessons did)?
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on September 15, 2017, 08:13:59 PM
that looks awesome.. nice upgrade to the gun just on looks alone
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on September 15, 2017, 09:09:07 PM
Paul - The barrel is not under any intentional tension.

Rob - Thanks for the approval on the new upgrade. I'm going to retire the older design that's on eBay and replace it with this new barrel housing upgrade, though the weaver rail won't be offered yet.

Also, thank you to the member that gave this thread a rating. I have no ideas as to how that works or why it exists, but I'll take it as a positive sign about the experiments!
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on September 16, 2017, 05:28:58 PM
 Since I have become totally distracted with improving the muzzles on longer barrels lately, I hadn't paid much attention to the clips. With my new awakening concerning pellet quality more time is being spent looking at them under magnification. Doing some pellet pushing through just the clip was instructive. It turns out that the pellets get mauled before they even reach the forcing cone at the breech. The main problem is the galling left by the ribs that are in the clip chambers.

It was mentioned by Scot L  early on in this thread  that taper reaming the pellet clips was useful. To that end I've now used various drill sizes to reduce the effects left by these ribs. It certainly reduced the severity of the damage to the pellets when they are visually examined, but I haven't done any shooting tests yet. To do a better job on the cylinders I ordered a .177 - .176 step reamer. It's a stubby aircraft type and looks to be ideal for this application. It should arrive in the mail today. If so, I'll get busy with it and see what level of improvement if can make.

I'll take some pictures and report on what the results are.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on September 16, 2017, 08:53:52 PM
The step reamer arrived in the mail today. I had said that the step was .177" - 176". Actually it's .178" - 176". The .178" bore that is left after reaming seems to be an excellent fit for the RWS Basic Line wadcutters pellets. The skirts on these pellets all measure close to .185". The skirts on the Crosman Competition wadcutters runs from ~.176" to ~.182". I can see where the cylinder ribs would be a way to keep poorly made pellets in the clip. I'll do some shooting tomorrow and see what the new clips do for velocity and accuracy.

The photos show the reamer and the handle that I've mounted it into.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on September 16, 2017, 08:55:54 PM
looks perfect... that's a tiny reamer @
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on September 18, 2017, 06:51:39 PM


Measuring the head diameter on pellets can be tricky. Even if you use one of the commercially available sizers there can be questions about whether the head is really round or not. Putting the pellets into an assortment of precision holes won't necessarily give you good information on a distorted head. Before setting up the laser micrometer (a nontrivial project) I decided to cobble together a simple test method.

Since I can't seem to throw out anything I've accumulated a lot of stuff that can be repurposed for doing experiments. What came out of the junk pile this time is a platen from an old HP scanner. Any clean, flat, and smooth surface can be used, of course. The important part for making reliable measurements is a good digital caliper. It should read down to 0.0005" or 10 microns. It should have a thumb wheel for adjustment because the adjusting action needs to be very smooth with a minimum of stiction.

The caliper is placed onto the cleaned glass and a spacer is placed under it at the end of the scale. The spacer is used to keep the caliper parallel to the face of the glass without rocking. This arrangement works well because the measuring jaws are raised above the glass far enough for the jaws to touch only one end of the pellet. Since I'm now using wadcutters exclusively the pellets can be inverted and measured without any wobble. With the Jaws slightly open and the pellet remaining against the fixed jaw it can be rotated by the jaw for another measurement around the circumference.

It will take some practice to get the feel for making the measurements, but when you get there you'll find that it can be done quickly and with considerably less force than a micrometer needs. Also, there is no fumbling with trying to hold the pellet square while rotating the spindle. Repeatability on the same pellet is when you've arrived.

The photos illustrate the measuring arrangement.

 
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on September 27, 2017, 10:12:26 PM
After spending a lot of time working on the Vigilante and doing upgrades using the Crosman 1077 barrels it seemed logical to buy a 1077 carbine in its original form and see how it performs and what can be done with it as far as improvements.

Even just out of the box the Vigilante was impressive. I questioned how anyone could manufacture an airgun revolver this nice and sell it for only $50. Now that I've got a 1077 I have to ask myself how anyone could manufacture an airgun like this and get even $20 for It. I've spent the afternoon with my new nemesis, the 1077, and hope that I've got enough beer in the refrigerator to sooth my wounds and see me through this mega-disappointment tonight.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on September 27, 2017, 10:19:54 PM
very cool on the measurement set up.. Id imagine an air gauge would be more accurate, they are no longer made or extremely expensive.. another idea would be 2 precision ground plates ( think mill vise  parallel set ) stood parallel in a fixture atop a surface plate  that only clears .1770 and another next to it that clears whatever other size,.
the 1077 is a mess, I had one for 6 months , thought there was potential there, but the trigger killed all my ideas.. There is also an issue with the gas egress from the tube adapter to the valve, and there limits what can be fed to the valve per shot
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on September 28, 2017, 12:18:44 AM
If you go with the pair of parallels approach, they could be set up wedged at .001 per inch or so, pellet lateral position would indicate size
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 03, 2017, 10:22:16 PM
Now that the muzzle crown and choke treatments are working out so well it seemed reasonable to look a little deeper into the barrels again. The last time I looked it was with the cross sections of 1" slices of the original 6" factory barrels. This time I'm looking down the whole barrel with the notion that any improvements can be tested directly by just putting the barrel back into the gun and doing some shooting.

Since I can't see very far into the muzzle or breech with the microscopes or just the camera lens without destroying the barrel I've decided to utilize the Storz/Hopkins borescope to get a better look. Just looking down the bore with the unaided eye proved to be quite deceptive. There are 10 shiny swirls and as many dark, mostly non-reflecting swirls evenly spaced down the barrel.

Way back when I was doing the sections and looking at them with a microscope the shiny parts of the rifling were identified as the lands. It's actually the opposite. If you go back and look at the photos from then you'll see the parts of the rifling that I referred to as "worms" are actually the face of the LANDS! How embarrassing! There's no fool like an old fool.

Anyway, my apologies for the misinformation. I stand corrected and am ready to move on. The borescope will now turn into an excellent tool for evaluating the method that I've chosen to deal with the refacing of the lands. It will be somewhat of an offbeat method of lapping then what is conventional, but that's what keeps me interested in all of this stuff.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 07, 2017, 07:08:44 PM
Most of the shooting that I do is from a vise. I'm interested in the effects of barrel treatments so the gun must be taken from the vise to change barrels. The same thing goes for installing and aligning the different optics. I usually just sight down the bore to be sure that I can at least get on the paper. The carbines are generally more awkward than the pistols using this method.

I finally broke down and bought a laser bore sighter from eBay. The one that I chose is a generic one from china, though some of these are branded. I try to get info about stuff by reading reviews on sites like Amazon. The reviews that were available for this device seemed to make this purchase a bit of a crapshoot, but for less than $20 I was willing to take my chances.

It finally arrived a couple of days ago and I got to play with it this weekend. As reported in the reviews it has some really crummy adjustable adapters and I can see where many owners had plenty of room to complain. The sighter that I ordered was for a bore range from .22 up to much larger calibers. My usage would be mostly .177, so I knew that I'd have to make my own arrangements for stabilizing the bore alignment.

My solution was to bore out a couple of wadcutter pellets on the lathe and use them with one of the provided screws to fashion a .177 adapter. The rifling in the barrel helps to keeps the pellets concentric with the bore. They work far better than the rubber ones that come in the kit. Once the pointer is installed into the bore it can be rotated to check the axial alignment. There were several complaints that the alignment was poor and when the laser is rotated it describes a circle of various diameters on the target. Mine was no exception.

There is a hex wrench included with the kit and it allows you to adjust the position of the laser on the target. The nice thing about the adjustment screws is that there are 4 apposing set screws that adjust the alignment. The bad thing is that there is only one wrench to work with. The alignment becomes virtually impossible with just one wrench because when you loosen the screws the laser can loose contact from the battery circuit. This contributes to more than one problem.

Anyone who has tried to center work in an independent 4 jaw lathe chuck using only one chuck key knows what I'm talking about. The solution is to get a second hex wrench and use it to allow the simultaneous adjustment of apposing screws by turning one in and the other out while keeping light pressure on both of them.  This process will keep the laser in electrical contact at all times and allow the dot on the target to rotate in smaller and small circles as you adjust its position. Replacing the supplied rubber pieces with a pellet(s) that fit the bore makes this an excellent instrument for bore sighting. I'm very pleased with the outcome.

As an aside, the complaints of very short battery life may be that the adjustment screws, as sent from the factory, are not snug enough to give reliable electrical contact with the laser.


Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on October 07, 2017, 07:50:21 PM
George,
It would be interesting, when you get the data, to see how the bore sighter  compares to pellets on target, at least in the horizontal axis.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 07, 2017, 10:38:38 PM
My method for adjusting the laser is to shoot a pellet somewhere on the target and then turn the set screws to line up the laser with the hole. This is all done with the gun in a vise. The sighter is self aligning at the muzzle because of the cone shape of the sighter's probe. The end that fits into the bore is kept concentric due to the tight fit of the pellets and the lathe centered drilled holes in them. The foible of this arrangement is that the sighter cone must be kept snug against the muzzle. This is where having a third hand would be useful. In lieu of that I use a rubber band over a front side of the laser and attach the other end to a lug on the scope. Under tension there is no movement of the sighter other than rotation. That leaves both hands free to tweak the set screws.

With little effort the sighter can be adjusted to rotate in a circle that just fits around the edge of the pellet hole in the target. It could be tweaked better I suppose, but it would offer no real benefit for my purposes. This is all done at 15 feet target distance at the moment. 
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on October 08, 2017, 02:38:39 AM
I guess the real question is , is the gun laser accurate at 15 feet from a vice?
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on October 08, 2017, 02:55:38 PM
George,
With the gun in a vise, if you take the laser out and put it back in, how close does the spot repeat?
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 08, 2017, 03:57:40 PM
I did the remove and replace test several times. The dot size at 15' is a nominal .20". After 10 tests the dot moves less than ~1/2 its diameter. My requirement is that I be able to put a shot group in each quadrant plus one in the center of a ubiquitous Gamo 5 1/2" target. I'm only interested in group size when testing different mods and different pellets.

The accuracy with this bore sighter far exceeds my requirements for the time being. I doubt that these results using drilled pellets to center the sighter could be reproduced if you had to use the adjustable rubber pieces that are provided. If anyone else is able to do the test using the factory setup as a comparison I'd be interested in the results. 
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on October 08, 2017, 04:25:40 PM
Those are good results.
Thanks
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 09, 2017, 03:40:42 PM
One of the things that is worth mentioning when using the 2 pellet method on the end of the sighter is that the screw holding the pellets should be snug, but not tight. The sighter should then be held lightly when it's inserted into the bore. This will allow the pellets to seat into the rifling which will cause the sighter to rotate about 1/4 turn as it's installed. This will assure that the axial alignment is true. The rotation should reverse itself when the sighter is removed.

Check that the screw is snug before each insertion. don't over tighten the screw because it will over expand the pellets and make it hard to insert. Also, don't use any glue or such on the screw threads.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 12, 2017, 10:03:12 PM
I've been thinking about the suggestions concerning the measurement of pellet heads. Typically the skirts are larger than the heads. This is a good thing for gas sealing.

The alternative methods that are offered for making this measurement, if I understand the descriptions properly, don't allow the head to be measured without compressing the skirt. the method that I've described raises the caliper faces above the skirt and only measures the head. Am I missing something?
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on October 12, 2017, 10:13:59 PM
the paralells could be elevated to  clear skirts I assume.
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on October 12, 2017, 11:06:06 PM
The parallels that I have are only 0.150" thick. I looks like, head down, the skirt on the RWS Basic wadcutter, is still smaller than the head when it clears the parallel.

For other shaped pellets, may need to do what Rob said and shim.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 13, 2017, 04:02:59 PM
Assuming that one's choice was to use Stan's method of thin parallels in a 'V' shape, it would not be difficult to electrically isolate each parallel at the vertex. A battery and LED could then be hooked up to indicate when the pellet filled the gap and lights the LED. This could produce an indication with very little pressure applied. It would probably make an interesting product. I'd buy one if it was priced right!
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 15, 2017, 07:22:52 PM
Measuring pellet head size can be a daunting task. The setup described previously using the shimmed digital caliper on a glass surface should make the job easy and fast. The problem is that the pellet can be rotated using just the fixed jaw. This allows the measurement to be made again at a new set of points on the perimeter of the head. This maneuver most often gives a new number from the last one taken. Thinking that the head may have been squished a little, the pellet can be rolled back to where the last measurement was taken. I then get the first number back again. Back and forth, round and round. It appears that many of these RWS wadcutters have oval heads or something that makes them look that way.

This turns a 5 second measurement into several minutes of frustration on each pellet. I'm now suspicious of the accuracy of the gauges that rely on round holes of various sizes as way of assessing the actual pellet head diameters. It makes me think that the round hole devices, even if they're fibbing, could still really speed this job up. I have no doubts that the gauge holes are accurate If they're measuring something that is really round, like a gauge pin.

I realize that I could be getting myself into hot water even mentioning this dilemma, but sometimes the curtain needs to be pulled back a little. Or I need to be corrected by those who are able to use both methods and determine if I'm doing something wrong.
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on October 15, 2017, 11:43:54 PM
OK George,
As you requested, I made the Size-o-matic 2000.
Works pretty well, as set up each of the tick marks is .001" from .173 to .182" (sorry for the cell phone picture).
I think I'll make up some gages and set it to a shallower wedge. Maybe .005" over 3.5"

But yes, I notice the wadcutter heads are not round and sometimes have a little flashing.

Not sure what I'll do with the data, but it was a fun sidetrip.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on October 16, 2017, 12:26:39 AM
that looks perfect , does it respond to continuity ??
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on October 16, 2017, 01:00:42 AM
Yes, the LED comes on just as you feel drag on the pellet. I added the red plastic to get the friction down, that way you don't jam the pellet into the wedge. For a particular pellet, the drag point and continuity are pretty repeatable. On some pellets the first time through, it feels like there is a little flashing, continuity occurs slightly before a softer drag point.

As set up, it is probably .0005"ish for pellets.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on October 16, 2017, 01:16:06 AM
excellent , what are the 2 wall  surfaces made from ?
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on October 16, 2017, 01:45:43 AM
They are thin parallels I don't have the specs on them but the edges are ground flat. I don't remember if I got them from LMS, but they are very similar.
https://littlemachineshop.com/products/product_view.php?ProductID=2924&category= (https://littlemachineshop.com/products/product_view.php?ProductID=2924&category=)

Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on October 16, 2017, 02:01:19 AM
gotcha.. I use a harbor freight 35 dollar set, and the fact is , theyre more accurate than I am  ;D
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 16, 2017, 03:50:52 PM
It looks as though Stan has come up with a third easy way to measure pellet head diameter. I like his because it provides a different and accurate method to confirm that the heads on many 'quality' pellets can be out of round by a significant amount. This leaves me to believe that the whole concept of making the measurement by any means needs to be reevaluated. I was a little nervous about reporting the finding because of the great following 'sizing' has. Please don't shoot the messenger!

This new information makes me think that there's much more to be learned about pellets and muzzles. It opens the door for coming up with some new testing methods. I'm hoping that this onion can keep showing us more rings to peel back.
Title: Re: Hacking the Crosman Vigilante
Post by: AmBraCol on October 16, 2017, 04:50:11 PM
I'm curious if anyone has measured any of the high end wadcutters, or just the "blaster" level of quality?  The reason I'm asking is, the Crosman and Gamo brands tend to be of VERY low quality control, no wonder there's a problem with oval heads. I've got a tin of Gamo "Match" pellets - that includes an obviously deformed "pellet" that made it into the tin from the factory.  Haven't taken time to measure them, but will be doing some photos and measurements one of these days.  Maybe I should break out some of my small stock of competition grade pellets and see how they measure up.   ;D
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on October 16, 2017, 05:39:57 PM
My exercise was to see how the wedge approach works in measuring pellets in general. I have not measured (or have) any quality pellets. To be honest, I do not know what the criteria should be for acceptable eccentricity for a pellet head. If it needs to be less than .0005" or so, probably need a more refined measurement.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 16, 2017, 07:33:56 PM
I checked some of the RWS Meisterkugeln Professional Line 8.2 grain pellets to see how the out-of-roundness compared to the RWS Basics and found that they both measure ostensibly the same. These are the best pellets I have at the moment because I'm just learning about good pellets. Since I'm using them in the mod tests for the vigilante at 15 and 30 feet I'm not putting big demands on the pellets, though these RWS pellets easily out perform the Crosman pellets in most of my testing.

I've read quite a lot about pellet weights and how some people think that's the magic metric. It would be interesting to look at the weight spread and compare it with the diameter spread. Then one could use Archimedes principal to determine weight vs volume issues. Putting it all together might be a good way to demonstrate how easy it can be to chase one's own tail. I seem to favor such endeavors. It's always the beer that brings me back to my senses.


Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 18, 2017, 04:51:52 PM
I've been considering some ideas about pellet mass and diameter. Assuming that the rules of dynamic unbalance are valid, it's useful to do a few thought experiments as they apply to a spinning pellet when it leaves the barrel. Basically the rules say that a rotating mass is in balance when the center of mass is in axial  alignment with the center of rotation. When this is not the case the rotating mass is said to be unbalanced.

A degree of unbalance can be attributed to the magnitude of a pellets unroundness, all other things being equal. A pellet that leaves the barrel at 500 fps will have an instantaneous rotational speed of 22,500 RPM. The stability afforded by gyroscopic stabilization may be offset by dynamic unbalance if the inertia axis is shifted far enough from the geometric axis. This shift of center of mass can also be attributed to a bubble or other such things.

Maybe Archimedes does have a roll in this drama. Time to get out the Jolly balance!   
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 19, 2017, 04:57:27 PM
There were a couple of questions about the accuracy and repeatability of a laser bore sighter that I recently bought. I addressed the repeatability part but didn't comment on accuracy because the short distances that I work with don't require great accuracy to get me onto the of the targets I use. The accuracy issue kept creeping up from some dark corner of my mind. Considering the use of pellets to guide the sighter on the bore's axis and that the laser is fully adjustable to follow the bore, I just left it at that.

Now that I've given it some more thought I have to tweak my mental image of what accuracy might mean in this scenario. So, here's my accuracy explanation. It's not so much about this sighter device as it is about every bore sighter device. I'm sure that this info is old hat to those of you who have been target shooting for a long time, so I'll just confess that I didn't give much thought to bore sighting until now. The other evening, after a few beers, I did a some calculations and a light came on. If the sighter was absolutely on axis with the bore, a perfect pellet traveling thirty feet at a constant velocity of 400 fps would hit the target a little more than 1" below the laser dot. In the real world the pellet would be slowing down some and would drop even more. That's in just 30 feet.

Since I hadn't given any thought to the magnitude and effects of gravity over such a short time span and distance I didn't differentiate the meaning of accuracy. The barrel can be very accurate and the sighter can also be very accurate, but a pellet and the sighter won't land on the target at the same place even at short distances. I apologize if I'm preaching to the choir.

   


Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 21, 2017, 08:14:24 PM
While amusing myself with the kinematic equations of late it seemed like a good time to test them out on my Combro chronometer. I set up a simple verrtical arrangement as shown in the photos.

Using a piece of 12" brass tubing it was a simple matter to align the tube with the Combro tunnel and drop a .177 pellet down the bore of the tube. The total distance from the drop point to the first sensor was 12.5". The calculations said the pellet should arrive at the first sensor in 0.25 seconds with a velocity of 8.19 fps. If the drop was clean, the velocity was consistent. If I heard a click or scrape the number was always slower by some amount. I asked a couple of other people with chronometers how they would test the accuracy of their instruments and the answer was to compare it to another instrument. I then asked what they would do if the two instruments didn't agree. In each case the answer was to get a third instrument. I didn't peruse the questioning any further.

This was a very satisfying experiment and may give others something to try.   
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 22, 2017, 05:24:12 PM
The $10.99 (w/free shipping) bore sighter from eBay is still an entertaining device for me and the cat. I've also been using it for 30' vise held target testing to see how good it really is. This is somewhat awkward because of the distance. Trying to do the laser adjustment while looking at a dot 30' away, even when it's in a clamped barrel, is still hard to do with my old eyes.

I needed a simple test to determine the true limit of axial alignment. The easiest variable to eliminate is the barrel itself. To do this the sighter was installed into a collet in the lathe. With the drive in neutral the chuck can be easily rotated by hand and the laser's center point then adjusted. I used the tailstock center as the target. The distance was 32" from the front of the pointer. The center's tip made a good target because the beam would move down the tip's side noticeably when it was off center.

The adjustments worked very smoothly and made centering easy. The next step will be to use a pair of front surface mirrors (the first one at 45º) to bounce the beam across the shop and back to a target placed at the starting point.

Following that will be to put a barrel into a collet and use the sighter in the barrel with the double pellet alignment arrangement and see what can be achieved.



Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on October 22, 2017, 05:26:38 PM
awesome.. did you make a center from brass just for this task ??
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 22, 2017, 05:33:14 PM
Rob - I think we got into a posting time warp. Which post are you referring to?
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on October 22, 2017, 05:49:08 PM
the dead center or live center used in the picture for laser alignement .. Did you make that just for this task , it looks fancy and new
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 22, 2017, 06:02:45 PM
Fancy and new? No, it's the same live center that I've been using regularly for the last 35 years. Thank you for the comment, though.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 23, 2017, 09:41:44 PM
Back to the Vigilante upgrades! I've been doing some machining and have gotten to the point where most of the parts can be assembled for a fit test. I still have to install a rail under the forestock so that a bipod and flash light can be mounted, but here's what it looks like now. When it's finished the the pistol grips will be swapped out for the shoulder stock.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on October 23, 2017, 09:43:52 PM
that looks awesome .. Any idea of the fps in this format ??
Title: Re: Hacking the Crosman Vigilante
Post by: dv8eod on October 23, 2017, 09:48:18 PM
 :o    If I hadn't been following, I wouldn't have recognized it as a Vigilante. 
Very nice work there.  8)
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 26, 2017, 10:59:13 PM
The Vigilante is finally morphing into the carbine I was hoping for. There are still some things that I want to experiment with on the barrel, but I'll do some shooting with this rendition for now. I think this one is going to be very good.
Title: Re: Hacking the Crosman Vigilante
Post by: Horatio on October 27, 2017, 03:03:44 AM
The Vigilante is finally morphing into the carbine I was hoping for. There are still some things that I want to experiment with on the barrel, but I'll do some shooting with this rendition for now. I think this one is going to be very good.

That’s what I think is cool.

Like a 1077 that can be shot single stage.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 27, 2017, 10:41:14 PM
Well, wouldn't you know it. Before I've even taken a shot with my sweet new Vigilante carbine I've gotten derailed by another project. It all started when I read a post last night in another forum where someone posed the question " Why aren't there any .22 cal mods for the Vigilante?" The OP was scolded with remarks such as  'it can't be done or someone would have done it by now' and 'certainly the OP couldn't do it because he had to asked the question in the first place!'. Then they listed the reasons why he was a fool.

I felt bad for the OP because I think it was his first post at that venue. Anyhow, suffering vicariously for the poor guy I got to thinking about their list of "Why it can't be done."

Rather than do the mod all at once in one post I'll just start with the easy stuff and move forward as progress is made. Tonight's effort was to deal with the pellet clips. The first and most obvious thing was to abandon the .177 clips. The BB clips are almost universally claimed as not being able to hold the BBs well. This was a hint that they may hold a larger projectile more securely. It was an easy task to make a fixture to hold the clips in the mill vise and drill the holes out to accommodated the .22 pellets. The holes index perfectly in the vise using the simple fixture.

Next will be to bore out the barrel housing so that the 2240 barrel that my buddy Dave gave me can be installed. I'll post some pictures tomorrow.


 
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on October 27, 2017, 10:55:07 PM
awesome , this would be a great kit to bring back the era of the 22 co2 repeater which mostly died in 2004 when the 2210 crosman was cancelled.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 28, 2017, 04:35:18 PM
Here are a couple of photos of the 6 round BB clips and the milling fixture. Centering, indexing, and drilling were quite easy to accomplish. next is to machine the 2240 barrel to fit the Vigilante barrel housing. I should have that done this afternoon.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 28, 2017, 09:15:25 PM
The time was well invested in the machine shop today. This .22 cal conversion of the Vigilante went beyond expectations. The machining of the 2240 barrel and the barrel housing was fairly routine. The most critical part of any of these barrel mods is the spacing of the breech end of the barrel and the clip. If the spacing is right the clip is suspended between the forcing cone and the detent cylinder. The detent cylinder is conical which allows it to be fairly self aligning.  This allows the clip to press itself flat against the breech. There should be no light that can be seen on either side of the clip where it's pinched. Leaving room to shim the barrel allows this pair of sealing points to be tight when the gun is fired. When everything is right there is a very distinct click from the detent cylinder when the clip is indexed.

There's still work to do, but the main part of getting the barrel into the housing worked out well. I took a couple of test shots to see how things were going and ....... well, you had to be there. At 85º F the power plant was not found wanting. It was a whole new experience firing a Vigilante! I'm now contemplating taking my previous .177 carbine efforts and throwing them all into a ditch!! 
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on October 28, 2017, 09:18:26 PM
that looks great ! nice job on the barrel fitment.
Title: Re: Hacking the Crosman Vigilante
Post by: Horatio on October 29, 2017, 01:52:31 AM
Nice!

That post answered a question in my mind about cylinder gap and power loss.
Title: Re: Hacking the Crosman Vigilante
Post by: AmBraCol on October 29, 2017, 10:27:39 PM
This post just keeps on getting more and more interesting!  Thanks for sharing with us, George! Looking forward to seeing how the 22 Vigilante works out.   ;D  So, you're using the standard 7" 2240 barrel, or one of the longer ones?
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 31, 2017, 09:18:07 PM
Machining the 2240 barrel (~7" long with the transfer port cut off) and Vigilante barrel housing has been pretty straight forward. The 6 round BB clips offered some challenge when drilling to size. There are 3 thin-walled fingers that are used to hold the BBs in place and they are made even thinner when machined. I'll admit that using a drill for boring out the .177" holes to .22" wasn't the best choice for the operation, but I didn't have a .22" reamer handy. I've since ordered one from eBay and will do the next few clips with that when it gets here.

The chances are that the fingers will still act as thin reeds and wobble around during the reaming operation, but I think there is a solution for keeping them solidly fixed in place. I have some water soluble machinable wax that has a melting point below the glass transition point of ABS. I'll try pouring some into the cavities of the clip before machining and see what happens.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on November 01, 2017, 06:08:34 PM
The .22 conversion is moving right along. There is still some detail stuff that needs to be done on the clips. Resizing the pellet holes requires a fairly critical alignment. The mill is able to hold the center without any problem, but the drill is just a drill and will never do the job well. I'm waiting for the reamer to arrive.

In the mean time I've been using what I've got and it's been instructive. After shooting about 30 rounds of Crosman Destroyers one finger in each pellet hole has disappeared. This causes the pellet to misalign with the bore axis resulting in a wide variation in the muzzle fps. Surprisingly, the accuracy still remains good at 15'.

When the first pellets were shot at 85º F I was getting about 340 fps. When the velocity dropped below 300 fps due to the clip damage I removed the clip and re-positioned the barrel up to the detent cylinder and got about 355 fps. The clip solution will probably be to sleeve and ream the pellet holes. We'll see.

Installing a longer barrel will help to boost the fps, but not as much as I'm after. The solution will be to add the longer barrel and some extra volume to the valve. There are a few ways to add volume and I'm looking forward to the challenge.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on November 01, 2017, 08:22:13 PM
excellent . these are very good baseline numbers for an action pistol.. the 2210 I had was designed for 22, made by crosman , also with the 7 inch barrel.. Numbers would start in the mid 370s , and drop off quickly thereafter.. Hammer weight and consistency was the key ..
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on November 04, 2017, 06:30:47 PM
The .22" reamer arrived a few days ago and was put directly to work. To my chagrin the pellets were barely being held in the newly reamed holes. I measured the skirts on a few of the pellets and they were all in the area of about .225"and should have had a snug fit. This didn't make sense, so I measured the reamer. Sure enough the reamer was actually .225". I've never owned reamers that weren't vanishing close to the numbers engraved on them. Thinking that I better order another one that calls out three decimal places I bought one from the same eBay sell that was marked .220".

The new (to me) reamer arrived today and was promptly tested on one of the BB clips. I first tried it in one of the holes previously reamed by the first tool and it didn't even fit into the hole! I then measured this second reamer. Lo and behold it was closer to .226"! Both of these reamers have the L. E. Wilson name on them and claim to be "inside neck reamers" and looked to be just what the clips needed. I don't get it. How can both of them be so far off? Is there some secret firearm dimensioning system?

Well, I gave up on this seller and will return the tools. I ordered another interesting looking (non-firearm) .220" reamer from a different seller today. I'm hoping that my luck changes.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on November 04, 2017, 06:42:02 PM
that's crazy/.. My reamers are spot on , with a few tenths or less. I'm sure the new 220 reamer make for machine shop use will be exact.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on November 11, 2017, 08:20:16 PM
I was doing some test shooting in the backyard today. I have the patio marker off at 30' and 33' from the vise to the target. Getting 1/2" and smaller groups with the new Vigilante carbine configuration is routine now that I've woken up to the need for better pellets. I decided to see what the groups looked like at 50', so a new measurement was needed to set up the target.

I've watched a lot of YouTube videos where people are measuring the distance with tapes or just pacing things off. I suppose that this works OK for whatever the intended accuracy might be, but generally folks don't have a tape that's longer than 50' and pacing can be a little iffy after a certain distance. The tapes can always be move from end to end if you're willing to deal with the inconvenience. Therefor, I'd like to report on my cheap solution to a quick and easy method.

For years I've been using a measuring wheel from Harbor Freight. It's the 1000' version and costs about $10. I decided to compare it to a $12, 100' open reel tape from the same source.

Now, I know the old Chinese saw about "Man with one watch knows what time it is, man with 2 watches never really sure." Since I'm using two different Chinese devices to measure the same distance I could have both feet in that trap. I decided that if they agreed to within less that 1% in 100 feet, either would be acceptable for my purposes. My preference is usually to use the measuring wheel for its convenience, but it still needed to be compared to the tape. I used the street as a testbed and both devices were within 0.5% at 100'. That's close enough for today. I'm sure that most of you are onto this method, but just in case anyone isn't, I'll claim that the measuring wheel is worth the money. 
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on November 11, 2017, 09:34:47 PM
Wheel?.....Tape?.....Harbor Freight???...
George, I was expecting you to reach into the bottomless instrumentation toolbox and pull out something with at least one laser.

To be fair, I have been eyeing some of the laser distance meters at home depot....just for the fun factor.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on November 11, 2017, 10:22:48 PM
Yes, I recognize and readily admit to the shame and humiliation of it all, but when I get past test bench dimensions I tend to use what my wife uses in her garden.
Title: Re: Hacking the Crosman Vigilante
Post by: AmBraCol on November 13, 2017, 12:41:35 PM
Wheel?.....Tape?.....Harbor Freight???...
George, I was expecting you to reach into the bottomless instrumentation toolbox and pull out something with at least one laser.

To be fair, I have been eyeing some of the laser distance meters at home depot....just for the fun factor.

Same thought here!  Saw a laser measuring device at Price Smart (local equivalent of Costco) - but it only measures to 100 feet and didn't see if it does meters (which would be more useful in our metric context in Coffee Country).

One issue between the wheel and the tape is the ability (or lack thereof) to keep the tape perfectly straight without stretching it out and thus distorting the measurement.
Title: Re: Hacking the Crosman Vigilante
Post by: Horatio on November 14, 2017, 01:15:56 PM
Experience with 100’ and 200’ lufkin tapes. You won’t stretch a quality steel tape enough to make a difference.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on November 15, 2017, 07:59:48 PM


The new .220 reamer arrived and it's a beauty. the 5º tapered lead is perfect for cutting the 3 fingers on the 6 shot clip and the spiral cut flutes don't catch the clip's fingers and break them off. I'll get some pictures of a finished clip when I'm done with the machining.

I'm still interested in exploring the aerodynamic aspects of pellets in flight. Now that I've spent some time on the muzzle treatments and started to use much better pellets there are only a couple of fliers in a group of 40 or 50 shots from the vise mounted gun. This leads me to believe that the problem now is with the pellets. I've weighed and measured them and found unsettling variations in mass, diameter, and geometry, but the differences don't add up to much when shooting at targets 30' away using wadcutters. The fliers are still a mystery to me. The only solution for getting to the bottom of it all is to build a micro wind tunnel of the subsonic type.

I've been studying various designs and decided on using the subsonic open return type. I've got to start somewhere. None of the designs appear to be particularly clever due to the simple nature of the devices. Also, none that I've looked at yet have been designed specifically to analyze low speed airgun pellets, but I'm sure there must be a few out there. Since I'm drifting off into the unknown and being totally naive about the true nature of pellet aerodynamics on the experimental level, I think it's appropriate to just jump off the cliff into a custom design.

Most of tunnels I've seen that are on the amateur level have used Home Depot materials and are generally much larger than what I'm planning to build. Also, they are almost exclusively of the horizontal type. This always requires some means of supporting the DUT (Device Under Test)  to be supported somehow within the test area. I'm going to build a vertical type that won't need any DUT supports. If I can achieve truly uniform laminar flow past the pellet, the pellet should be self aligning.

To make sure that the project remains far from the well beaten path I'll build the main structure out of glass. Something on the order of 1.5" diameter medium wall borosilicate glass should work handily. The whole device should be about 12" tall or less. I'll probably use compressed air instead of a fan to start with. It should be easy to switch to a vacuum pump to pull the air if the compressor idea doesn't work well.

The only major tool necessary to do a decent job on the glass will be a glass lathe. These aren't difficult to make if you start with a couple of Harbor Freight wood lathes. I know, I know, it's Harbor Freight again!

The photos are of a glass lathe that I built awhile ago to make some vacuum tubes. That was last year before I discovered airguns.
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on November 15, 2017, 08:59:05 PM
Glass lathe....very cool...off to Google I go....

How did you synchronize the two motors? They look like steppers...did you just run them open loop?
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on November 15, 2017, 10:59:52 PM
The motors are steppers run synchronously and originally driven by a Slo-Syn indexer controller. My good buddy Bruce decided to make a similar lathe and used a much more modern CNC stepper controller and graced me with a copy of his electronics which has more bells and whistles on it.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on November 16, 2017, 09:33:34 PM
The first attempt at a glass wind tunnel was made today. I'm using a NASA sample drawing of an 'open return' type design to practice on. The glass work is pretty straight forward to get started with. Refinements will be easy once I figure out what the real design turns out to be. There is some wind tunnel modeling software on the internet that will be a great help for determining guidelines.

Practice is all it will take to perfect the design. I like the glass as a construction material because it has no corners to cause perturbations in the flow. The walls are obviously very smooth and the transition areas are going to be easy to control.

The photos show the starting setup with the model drawing and the first crude tunnel. This is getting exciting because it's so simple to do. It's been said that you shouldn't step where you can't see the bottom. Well, what fun is that?
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on November 17, 2017, 09:11:57 PM
I did a couple of preliminary tests today to see what it would take to levitate a .22 wadcutter in a tube. I'm just after first approximations for now. The quick lash up was done in a plastic straw using compressed air. The regulator was set to 10 psi and the flow was adjusted using a needle valve. It was reassuring to see the pellet floating in the straw and not hitting the sides or rotating when the flow was adjusted properly. A slight deformation in the skirt was made and the pellet was retried in the straw. It wouldn't stay upright and began bumping the sides of the straw and rotating erratically.

This is a very crude test, but gives me a lot of encouragement to move forward on the mini wind tunnel project. The photos show what the quick tests looked like. I'm now convinced that the source of random flyers might be identified using the tunnel.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on November 17, 2017, 09:25:29 PM
perfect, id have assumed the balance point at which the pellet stays mid air stream would be harder to find.
Title: Re: Hacking the Crosman Vigilante
Post by: dv8eod on November 17, 2017, 10:28:26 PM
Another paper I found on my tablet you might find interesting. If it will post. I can't remember if I put it out there before.


Edit- Just noticed that it didn't upload. Sorry. I'll email it, George.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on November 18, 2017, 08:50:17 PM
The new tapered reamer got to do it's stuff today and it works perfectly. The tapered and spiral cut flutes allow the BB clip to be reamed from the finger side and it cuts perfectly without snagging the fingers. The .220 diameter measures correctly this time and allows the pellet skirts fit snugly into the solid part of the clip. The fingers make a slightly smaller hole because they can move partially out of the way from the reamer when it passes through.

The new clip was tested in a gun that was clamped in a vise. Using the 2240 7" barrel it makes a one hole group at 15' with no flyers. This is a good sign because I haven't even given it any muzzle treatment yet. This is all with RWS wadcutters so far.

I'm going to shoot up a bunch of rounds with the newly reamed clip and see if the clip fingers can hold up without needing to do anything tricky to keep them from coming apart. If the clip turns out to be reliable for lots of shooting I'll start to work on increasing the valve volume. This project may end up being another eBay offering down the road.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on November 18, 2017, 08:59:43 PM
I will say this , if you offer a 22 conversion for the vigilante on ebay , you better be ready to go full time !  ;D
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on November 22, 2017, 10:28:31 PM
I spent some more time machining the 6 shot clips today and the new reamer is working perfectly. With the new fixturing in the mill the precision of the drilling and reaming has been improved. The improved clip alignment with the forcing cone has now increased the muzzle velocity to run fairly steady between 350 and 375 fps @ ~ 80º F with rapid cycling. This isn't really great performance in the overall scheme of things, but it's an improvement. I'm going to order some longer barrels from Crosman and see where things get to before hacking the powerplant.

Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on November 23, 2017, 01:08:12 AM
looking very nice.. at some point , the barrel length will outweigh the available gas.. But when that is , who knows.. I'm guessing a 14 inch barrel would be a great starting point , and even the 10.3 incher would in theory get  you over 400 fps.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 06, 2017, 10:53:26 PM
Now that I've started the Vigilante .22 cal project it's obvious that I'll need to get more gas into the valve section. At the moment it seems reasonable to increase the volume of the valve and to enlarge the transfer ports. It all looks pretty straight forward with some simple machining.

The volume of the valve can be increased about 20% initially by machining some grooves into the inside wall of the valve body. The wall thickness is nominally 0.100" thick. By cutting some grooves into the inner wall and leaving some space between the groves I should be able to leave small sections of full wall thickness that will act as sort of inverse barrel hoops to deal with the pressure.

The photos show the setup to measure the inside wall uniformity and also the wall thickness. I'm using a Starrett back plunger dial indicator arrangement for the lathe measurement. It's virtues are that it's an easy measurement and it can reach further into the valve cylinder than the typical test indicator. It also gives me reliable axial alignment for setting up the grove cutting tool.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 06, 2017, 11:11:27 PM
very nice setup ! looking forward to the gains produced !
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on December 07, 2017, 02:35:33 AM
The full thickness section barrel hoops will not help with the axial strength of the valve wall if you thin it too much in the grooves. May be worth running some quick numbers to make sure you have sufficient margin.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 08, 2017, 04:00:27 PM
Assuming that the valve casting material is ZAMAK 3 (a safe bet) and using Barlow's Formula, the burst strength of the valve walls when thinned to .035" should be in excess of 3000 PSI near room temp. This would be without any internal hoops. I don't plan on the working pressure getting above 1000 PSI.

The longitudinal forces at 1000 PSI have a safety factor of at least 10 under worst case conditions.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 10, 2017, 07:42:51 PM
Up until now I've been using split ball bore gages to measure the effects of muzzle treatments and general small hole dimensions. The down side of these instruments is that they require a transfer measurement to get the numbers. This method will allow for only one static measurement at a time. This makes probing the bore at more than one place slow and tedious. Also, the radius of each 1/2 ball is generally too large to get a measurement down to the bottom of the grooves in the rifling so you're left with only the bore diameter at the lands.

I've just acquired a dial type bore gage that uses a different technique. It's a vintage Federal Products instrument that makes dynamic measurements as you continuously probe around in the private parts of a bore. It will reach in 2 1/2" and reads directly to 0.0001" It can easily be interpolated to 1/2 of a tenth. There are 12 probes that come with the set and each probe has a range of 0.008". The full range on this set is from 0.122" to 0.250". This will cover the barrel bore diameters of interest to me now. The use of setting rings is a big help in setting and calibrating the probes, but a good micrometer can also be used, thought it does make for an awkward measurement.

Besides the dynamic reading capability, I like the radius difference between the larger and longer fixed anvil and the smaller radius of the moving ball anvil. The ball can get down into the bottom of the grooves and the longer fixed anvil can straddle the grooves while staying on the faces of the lands. This allows accurate step height measurements of the rifling.

The photos show the basic arrangement of the instrument.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 13, 2017, 10:11:49 PM
The project to expand the volume of the valve by removing material from the ID of the valve body seemed pretty straight forward. The calculations indicate that the remaining wall thickness was safe at typical operating pressures. The problem with the approach of removing material is that I can't put the material back in if need be. After studying the situation through the lens of a few extra beers the solution came to me in the form of another one of my visions.

I'll make an adjustable volume by adding an appendage to the side of the valve body that can be exchanged for different sizes as needed. There's quite a bit of room between the pistol frame halves to accommodate these extra volumes. Starting with a piece of 1/4" 12L14 steel rod, I'll bore out a blind hole to some yet to be determined ID. The open end can then be threaded to 1/4"- 40. The valve wall can be threaded to match. Loctite red can them be used to seal the threads. Using the same threading arrangement will allow the change of appendage volumes without having to do any more machining on the valve body.

The photo shows the basic tooling needed to accomplish the task.

 
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 13, 2017, 11:10:24 PM
excellent idea and that will add a lot of volume if needed.. I'm sure just the extra 1/4 rod and the base valve volume should get you into the 400s/.. I don't recall the barrel length as it sits, but if still at 7 inches 10 would be great
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 16, 2017, 10:24:45 PM
It turns out that I can put 3 of the volume enhancing stubs onto the valve body to increase the flexibility of tuning the powerplant. They can be installed at 90º to each other and there's plenty of room to make the valve bristle with ports to add pressure gauges or other measurement devices. The pistol frame will still be easy to assemble and disassemble without the constraints of trying to fit everything inside. I'll try using Loctite Blue for starters and see how it holds up. I want to be able to take the threaded joints apart to re-machine the stubs for different measurements. Pressure wise the 12L14 won't be a problem, but this ZAMAK 3 is like machining cheese. We'll see what gives first. Hopefully neither one.

The photos show where things are now.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 16, 2017, 11:27:36 PM
makes sense , good thing you used a super fine pitch
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 17, 2017, 09:54:17 PM
Now that the .22 cal Vigilante is looking more viable and the valve volume can be increased easily, I wanted to try and seal the breech end of the barrel better than just the clip being pressed against the bare metal. Today's exercise was to see if an o-ring grove could be trepanned into the face of the barrel. I looked into the ready available trepannig tools and they were all dedicated to a narrow width selection and they weren't cheap.

The solution at hand was to mount the Dermel into the tool holder again and use any of the available bits that I had. The selection of these bits out there from many sources makes this rotary tool exceptionally versatile and limited mostly by one's imagination. Anyhow, the test was done on a piece of 12L14 steel and the results were very promising.

The photos show what the method looked like. This is all preliminary, but it looks like an o-ring seal can be easily add to the breech of this .22 upgrade.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 17, 2017, 10:29:30 PM
perfect ! I wonder if this will lead to a measurable gain
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 19, 2017, 10:45:55 PM
There's no denying that I'm caught up in the world of CO2 as the powerplant for making carbine mods, but the world of PCPs is hard to ignore. They're surely the wave of the future for a large segment of airgunning. I've read quite a bit about various attributes of this newer (?) species and have watched several YouTube videos where the proud owners are extolling their new gun's virtues. It's  inevitable that I'll end up there sometime in the future. For now it seems that time is on my side as I watch the price of entry sliding downhill fairly quickly.

Many of the videos make a point of showing that their PCP gun comes with a pressure gage built in. Realizing that my carbine's lack of a pressure gage is like driving around in a car with whitewall tires, I decided to get my builds into the 21st century by following suit.

Since some of my valves are getting modified with stubs I decided to add a gage and see how it looks. I really enjoy the steampunk trends that are out there now and the Vigilante carbines are headed in that direction.

The photos shows a crude proof of concept, but it works.


Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 19, 2017, 11:15:16 PM
that looks great..actually opens the door to later HPA experiments.
 
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 20, 2017, 10:49:13 PM
Now that the valve section of the Vigilante powerplant can be probed intimately with stubs it will be a good time to install an electronic pressure transducer directly into the valve's volume. Interesting experiments can now be arranged so that the accelerometer on the hammer can be used again to trigger a timed sequence of the valve opening and closing while still another pressure transducer can measure the muzzle pressure/time information. A transducer can also be installed into the side of the barrel just after the forcing cone to look directly at the pressure as the pellet is released from the clip.

I've been buying up some real sleepers on eBay in the micro-transducer realm along with the electronic amplifiers and conditioners needed to interface them to readouts. Several  simultaneous measurements can now be made in real time. The treasure trove of what's available on eBay for doing testing and measurements is truly staggering. It seem that the more exotic and esoteric the instruments are the more cheaply they can be acquired.

I'm now 1 year into this airgun fantasy and never though it could be this rewarding. I'd have probably lost interest by now if those of you following this expedition hadn't been so supportive and patient along the way. I've learned a lot. Thank you all!

Now for another beer!


Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on December 21, 2017, 01:33:24 PM
George,  I'm looking forward to when you can tie the entire timeline together. Would a photo diode or even just a broken wire at the muzzle establish pellet exit?
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 21, 2017, 11:47:47 PM
The collection of transducers that have fallen from the sky, with the help of eBay, have greatly enhanced the measurement capability of my test bench. My favorites for pressure are the Endevco 8530B series instruments. These are miniature devices that are threaded for 10 -32 holes and have assorted pressure ranges. A close runner-up is the Kistler 601B series piezoelectric instruments.

For transit time initiation signals there's not much that can compete with the Endevco mini accelerometers like the 2250A Isotron previously described. As far as muzzle exit signals go there are a variety of methods to trigger when a pellet exits. I've found the trip wire method to be tedious and less than reproducible for these measurements. The photo diode is a good method for getting timing signals and has the benefit of being none contact. The short coming of both of these methods is that they only provide an on/off signal. This signal is OK on many levels, but provides no other information.

My choice at the moment for exit timing is still the same as described in earlier posts using a Bruel & Kjaer force transducer. With this type of device set in position at point blank range at the muzzle the signal provides both timing and impulse energy information. This is a two-fer and saves the need for an extra channel to collect data.

This is my thinking at the moment, but it can easily be changed when new capabilities arise.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 24, 2017, 09:11:23 PM
The extra valve volume project got some attention today. I read in some Vigilante posts that the disassembly and reassembly of the valve can be a vexing problem. I've improvised a method that simplifies the exercise and reduces the number of required expletives to a minimum. I use tongue and groove pliers with the fixed jaw clamped in a vise. The clamped jaw has some washers of the appropriate size stacked on it to allow the valve stem to extend past the front face of the valve when the spring is compressed. The moveable jaw is used to compress the valve spring with the help of a 22LR case. The primer end of the case has been drilled out so that it can be slipped over the valve stem and protect the the stem and seal while the circle clip is being installed.

Since the clip manipulation is usually a two hand job, The pliers handles can be kept compressed using some rubber bands or an o-ring. The pressure gage and extra volume stub will be installed after reassembly.

The photos show the usual arrangement for executing the "clip ring maneuver".


Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 24, 2017, 09:20:04 PM
the third hand in the shop that's never there, nice rig
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 27, 2017, 07:05:40 PM
It's been a good year for playing with airguns. I've gotten to use a lot of dormant instrumentation to enhance my understanding of how CO2 guns work and what some of their limitations are. My goal up to this point has been to design and implement a carbine style rifle from a Vigilante pistol. What I wanted in the end was a light weight, multi-shot, double action, CO2 powered gun that was accurate at 30 feet and was reliable. That idea has now been reified.  I've learned a lot along the way.

I started to work on a .22 cal version of the idea using the Vigilante again as the foundation. The test bench results were promising. Then I started seeing promotional stuff from an assortment of sources that were showing off a new version of Snow Peak Airgun's CP-1 pistol. This new gun, the CP-2 has most of what I was interested in building and it's only $150. This model also comes with a shoulder stock, 2 barrels, 2 magazines, and a nice looking attachment that screws onto the threaded end of either barrel. I'm assuming the this attachment is purely ornamental and serves no real purpose. (?)

Anyhow, I've once again succumbed to the sirens and ordered a CP-2 from Mrodair. It should be here any day now. It's a left-side cocking .22 cal version and will probably put a damper on the .22 cal Vigilante project. I'm looking forward to switching the test bench experiments over to the new gun. It seems like an appropriate way to bring in a New Year. We'll see.



 
Title: Re: Hacking the Crosman Vigilante
Post by: WhatUPSbox? on December 27, 2017, 08:53:34 PM
George,
This has been a great thread......I have a CP-1 so I'm looking forward your new experiments.
Thanks for all your efforts
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 27, 2017, 09:01:13 PM
I'm sad not to see the expanded valve 22 test  :'(
Title: Re: Hacking the Crosman Vigilante
Post by: AmBraCol on December 28, 2017, 11:48:05 AM
This has been an interesting thread, indeed.   Looking forward to your next one!
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 01, 2018, 08:18:30 PM
The New Year is here, but my new SPA CP-2 isn't, so I thought I'd get ready for it's arrival by expanding the test bench capabilities. This small compressor is something a friend gave me many years ago and it has been sitting on the shelf ever since. It's now time to put it into service for working on some residual ideas for the Vigilante and to help with the testing on the CP-2 when it arrives. I hadn't even tested the compressor until today so it was satisfying to see that it actually works. Works as in "I put some oil in it and powered it up".

It has no tank, lines or gages yet, but it does run smoothly and quietly with no load except my finger over the outlet. If it actually produces useful pressure in the CO2 range it will be a boon for doing reproducible tests of all kinds. This will be an exceptional year for the test bench when it all comes together.


Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on January 01, 2018, 08:35:44 PM
cool! what pressures will that compressor run nominal ?
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on January 01, 2018, 09:29:03 PM
This is the only info I can see on the unit, but if it works in this range I don't think I could have asked for a better mini compressor for CO2 testing.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on January 01, 2018, 09:58:28 PM
wow, that's excellent
Title: Re: Hacking the Crosman Vigilante
Post by: classicalgas on January 20, 2018, 08:49:13 PM
" If the spacing is right the clip is suspended between the forcing cone and the detent cylinder. The detent cylinder is conical which allows it to be fairly self aligning.  This allows the clip to press itself flat against the breech."....that was my experience when i was accuracy tuning the cros 357  twenty years ago...a slight chamfer, or the larger chambers of a .22 cylinder, enhanced accuracy a great deal.

The down side was rapid wear of the cylinder hand, it's plastic and not up to the task of rotating a cylinder with solid detents.

I've done  a half dozen.22 conversions to the 357/Vigi over the years, it's not hard to do. A long taper reamer, carefully controlled in the old six shot clips is the hardest part. With an 8" barrel, I'd see 400 fps with light .22 pellets on a warm day from a well set  up gun.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on May 27, 2018, 09:26:23 PM
I've been spending my time experimenting with the CP-2 airguns since the Vigilante project was put on the back burner a few months ago.

Now that some of the CP-2 testing is overlapping with some earlier Vigilante experiments it seems like a good time to point out that there may be some interesting information in that thread for the Vigilante followers, too. It might be worth a look.
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on May 27, 2018, 09:28:54 PM
I RECENTLY did some pcp testing with my vigilante.

the gun certainly has its limitations with the valve and hammer config

http://thegreencrosmanforum.proboards.com/thread/3/project-1857-continued-old-green (http://thegreencrosmanforum.proboards.com/thread/3/project-1857-continued-old-green)
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on November 22, 2018, 05:54:16 PM
Organizing my workbenches is not one of my strong suits. I was going to make amends and reform myself in that activity as a resolution come New Year. Today was going to be a practice day. Well, it didn't go as planned, but I did attempt to assess the heap of stuff that was once the Vigilante project. Some of the parts that were protruding from one of the piles reminded me that a .22 cal conversion had been underway just when the CP-2 Sirens began to sing.

As usual I began to quickly drift off course and had a recollection of the 2240 barrel that was undergoing modification. One of the mods included shortening the barrel to remove the original transfer port. It occurred to me that it would be interesting to get another 2240 barrel and keep the port to mount a pressure transducer there. Some interesting comparisons could be made with the CP-2 pistol.

This would give me an opportunity to "Reload"(?) the thread as The Vigilante Hack Version 2.0. We'll see what the New Year brings.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on September 30, 2019, 03:18:48 AM
The Vigilante project has fallen by the wayside ever since the CP-2 found it's way into my small arsenal of airguns. The latest endeavor has been to develop an instrument for determining a pellet's energy at the target as opposed to it's energy at the muzzle.

Now that the KZQ (Kill Zone Quantifier) has emerged as my current instrument design boondoggle it seems appropriate to take another look at the Vigilante variants that have evolved over time on the test bench.

The idea that a revolver pistol might be the answer to my rat control issues at close range (those thoughts started all of this a couple of years ago) it now will be interesting to see what the capability of these pistols might actually be.

The KZQ transducer will be able to evaluate the real ability of the CP-2 and the Vigilante to humanely dispatch a rat at some predetermined distance. This evaluation will only be in terms of pellet energy at the target distance and not the ability of the shooter to actually hit the target in the kill zone.

With that said I'll refer those interested in the test results to take a look at the KZQ project as it exists now starting on page 20 of the CP-2 thread. I'll post the test results of the Vigilante pistols in this thread.

My thanks to all of you who have continued to be interested in this wayward journey! 
Title: Re: Hacking the Crosman Vigilante
Post by: AmBraCol on October 07, 2019, 05:20:49 PM
Definitely enjoying the ride.   ;D
Title: Re: Hacking the Crosman Vigilante
Post by: JnJHess on October 07, 2019, 05:54:28 PM
Paul - The barrel is not under any intentional tension.

Rob - Thanks for the approval on the new upgrade. I'm going to retire the older design that's on eBay and replace it with this new barrel housing upgrade, though the weaver rail won't be offered yet.

Also, thank you to the member that gave this thread a rating. I have no ideas as to how that works or why it exists, but I'll take it as a positive sign about the experiments!

You really doing a great job with all the analyzing and testing on these specimens. I have a Crosman Vigilante too. But it is but stock. I don't know If I have not read any parts of that you are offering these improvements on ebay, might have overlooked it.
But all what you doing sounds really interesting to get on any Vigilante.
Can you please tell me the name of the store for the parts that you offering there, or do you have a link to it.

Again I couldn't even imagine doing anything in the way you are analyzing and testing these things out like it.
I really lift my hat for your endurance, knowledge and followthrough you are doing in the science for our sport.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on October 07, 2019, 10:52:45 PM
The Vigilante parts that were sold on eBay came from basically just a few experimental builds back then. There are no replacements.
Title: Re: Hacking the Crosman Vigilante
Post by: George Schmermund on December 14, 2019, 11:16:31 PM
The Vigilante experiments have come back to mind recently. That .22 cal hack was making some headway as best I can remember, but the Sirens of the CP-2 became more compelling. Upon reflection I can see where the idea of a .22 revolver with an extended barrel would have some merit. The problem at the time was that the volume of gas available from the original valve body really didn't seem to make the upgrade that useful. Everything else was sort of worked out. The added volume of the extension stems didn't do what I was hoping for and the distractions for moving on to the CP-2 took control over the experiment arena.

During an idle moment a few days ago it occurred to me that heating the powerlets to keep the gas pressure within a certain range wasn't and wouldn't ever be as effective as directly heating the gas within the valve itself. To that end a vision of an RC hobby engine's glow plug appeared. These devices are at a scale where they could be fitted into the wall of the valve body and heat the gas directly in the valve's volume. The startling part is that I was sober when all this came to me!

The photos show an old hack on one of the pistols from the early days. The later add-ons were the pressure gauge and a volume increasing stem that is now replaced by the glow plug. This is just a mock-up for now, but the fit looks good so it might work. I need to get a tap that I assume has a 1/4 - 32 thread to match the plug.


Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 15, 2019, 12:25:28 AM
Great idea. I've run that valve@ 1800 psi no issues so as long as you can control the final temp you're good
Title: Re: Hacking the Crosman Vigilante
Post by: dv8eod on December 15, 2019, 01:44:15 AM
Out of curiosity, would the placement of a platinum wire serve the same purpose? If I recall, the wire generates heat under slight pressure, but I think it has to have a reactive gas. Been so long since I've thought about it. Catalytic converters use that principle, but the exhaust already has a headstart being hot exiting the manifold.
If it would work, it would cut down on the amount of machining to be done.
Title: Re: Hacking the Crosman Vigilante
Post by: Tom Tucker on December 15, 2019, 10:13:38 AM
Great idea. I've run that valve@ 1800 psi no issues so as long as you can control the final temp you're good

Did you have to modify the valve or hammer so that it would crack open at the higher pressure?
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 15, 2019, 04:05:22 PM
Great idea. I've run that valve@ 1800 psi no issues so as long as you can control the final temp you're good

Did you have to modify the valve or hammer so that it would crack open at the higher pressure?

no.. i modified the hammer though.. the way its set from the factory , the hammer is self limiting in  stroke.. I ran the gun as a pcp for quite some time.. Interestingly enough , even with a machine shop and many previous projects to base my assumptions on i never hit impressive numbers.. really just a hair above factory, although the shot to shot consistency was super impressive , almost like a regged pcp
Title: Re: Hacking the Crosman Vigilante
Post by: Tom Tucker on December 16, 2019, 11:53:09 AM
That's good to know.  I have one of these, but I never really tore into it.

It's the one that comes with 3 barrels, 3-inch, 6-inch, and 8-inch.  I like it a lot, but it's no powerhouse.  7.6 grain at 460-470fps with 8-incher, 420-430 with the 6.  The biggest advantage to the 8" is that it quiets the gun down.

I think George said on the second page of this thread that the valve volume is very small.  There's definitely something holding these guns back.  I thought it might be losing too much gas between the valve/clip/barrel, but maybe it's just not able to dump the gas fast enough...
Title: Re: Hacking the Crosman Vigilante
Post by: Rob M on December 16, 2019, 02:10:45 PM
That's good to know.  I have one of these, but I never really tore into it.

It's the one that comes with 3 barrels, 3-inch, 6-inch, and 8-inch.  I like it a lot, but it's no powerhouse.  7.6 grain at 460-470fps with 8-incher, 420-430 with the 6.  The biggest advantage to the 8" is that it quiets the gun down.

I think George said on the second page of this thread that the valve volume is very small.  There's definitely something holding these guns back.  I thought it might be losing too much gas between the valve/clip/barrel, but maybe it's just not able to dump the gas fast enough...


valve volume is the main issue