Hacking the Crosman Vigilante

[George Schmermund]

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.

   

[Rob M]

awesome, always wanted to see one of these pushed to the limits

[AmBraCol]

Subscribed - and hoping for pics.  :-D

[George Schmermund]

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!

[Rob M]

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.

[George Schmermund]

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.

[Rob M]

thsat looks incredible , sorry i missed the 10 inch part!

[UCChris]

Looking awesome!

[TleVta]

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

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

[George Schmermund]

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.

[George Schmermund]

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.

[AmBraCol]

Now to find a way to make it portable...

[George Schmermund]

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! 

[Rob M]

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

[George Schmermund]

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. 

[Rob M]

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 ?

[George Schmermund]

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.

[Rob M]

Sounds good ( no pun) keep pluggin away!

[George Schmermund]

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.

[classicalgas]

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.