GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: aPpYe on November 07, 2015, 04:52:49 PM
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Hi All,
It seems that I DO have free access to a lathe and a milling machine through work! Woo hoo! The mill works both manually and is computer programmable, I guess that means CNC? The lathe is manual only. Of course, I never even took machine shop in high school. I have zero skills in this area. I uh, did give myself a concussion once by running a wood lathe at max speed on a fresh 6x6. High school was fun!
Anyway, this being the case, and now that I have the money cobbled together for this, I figure I might save a little by bottling and ninja regulating a CCS 2400kt with a 24” barrel, rather than buying a Disco and doing the same. I have thought long and hard about going with the QB line, but at nearly 7 pounds, they might be uncomortably heavy after carrying around for a while. I have noticed it seems there is a general consensus in the community that the QB barrels tend to be of higher quality, so I recognize that I may be looking at fitting an aftermarket barrel if I am unhappy with the accuracy.
I figure it is mostly going to be used for plinking and some target shooting, NOT scoped and with peep sights. I may hunt some with it, but I figure I have my steroid silver streak a couple of powder burners for that. Having a lot of power is not really what I am after. That being said, higher velocities (sub transsonic, of course!) are a must, as I want to reach out as far as possible with minimal sight adjustment. I would like to shoot accurately at 50 yards if I can. I figure I should go with .177, as it will get me higher shot counts (I am even considering the 22ci ninja regulated bottle I see at MAC1!) and it will be easier to get to the 850-900fps range with 8-10 grain pellets. Please correct me if I am wrong with these assumptions, I know that the the larger calibers tend to be more “efficient” psi/fpe wise.
I see a lot of people going with the 13/3000 ninja regulated setup at various pressures. I have seen it preached many times that I want to have two “burst discs,” typically with 3000psi at the bottle and 1800psi at the regulated side, to keep things safe. I would like to keep the pressure as low as possible to keep shot counts up anyway. Are the ninja regs the only ones with this dual burst disc feature? Any thoughts on safe pressures with these guns? At what psi would I need to start adding pins to the valve? I don't want any bombs going off.
What can I expect velocity-wise with a 2400kt on say, 850psi out of the box? What about something like 1200psi? I notice that the tubes are pretty short. Is 875fps with an 8 grain pellet even feasible with this setup? What about 10 grain or higher? Am I going to have to start looking at longer tubes? Should I be looking at aftermarket valves and whatnot, or can can this novice machinist expect to be able to succussfully modify stock components with the aforementioned limited skillset? I am planning on learning the basics with these machines on throwaway pieces of metal and whatnot.
I have been researching these Crosmans for a few days now, and noticed the huge aftermarket for them. I see aftermarket valves, tubes, triggers, RVA's, just about everything. It seems, like the ruger 10/22, I can pretty much build these crosman 2xxx guns without ANY Crosman parts!
I am extremely close to finally making a decision on this!
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I can't speak for .177 but I'm hitting 620fps with 14.3 gr .22 pellets in a 2250 14 inch barrel on 850 psi. It has a lightened hammer, and a 1322 spring.
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IIRC, the tube on a 2400 KT is the same length as a 2250 tube, is it not?.... Making that assumption, and using a tank block similar to a QB79, you would have a plenum volume of about 24 cc (without a gauge block, or 17cc with one).... That is plenty for up to 24 FPE (17 FPE) with good efficiency, so your setpoint pressure will not have to be increased to look after plenum size.... 850 psi of air will give you more velocity than you get at room temperature with CO2....
With 1200 psi, you will get about the same velocity as a stock Disco at the bottom end of the shot string.... That means about 800 fps with 14.3 gr. pellets in .22 cal with stock porting.... In .177 cal, getting 850 fps with 8.4 gr. pellets should be equally available, maybe a bit more.... I had one set up for FT at 20 FPE, which is 10.3 gr. pellets at 900+ fps, but that took 1500 psi (which you can still do while using a 1.8K burst disc).... So, you can do pretty much everything you have in mind by using 1200 psi, but if you want to push the 10 gr. that fast, you may need to go to 1400-1500 psi.... Once fully sorted, my .177 FT gun got over 100 shots at 19+ FPE from a 13 CI Ninja tank at 1500 psi.... A bigger tank would give you proportionately more shots, of course....
One thing I can't stress enough.... MAKE SURE YOU ATTACH THE VALVE WITH THREE SCREWS.... I would use a Disco valve and screws for what you want to do.... and make sure you drill the tube accurately so that the two side screws are taking their share of the load.... If you want even better screws, you can use the valve screws from a PRod, but make sure you drill the holes in your tube to fit the heads (they have smaller heads than the Disco screws).... However, the bottom hole valve hole in the tube is already the correct size for the PRod screws....
Bob
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Wow Bob, those numbers are more than what I was expecting! I was thinking I was gonna hear about how I needed to do all kinds of modifications to achieve what I am after!
From what I understand the tubes are of identical dimensions
Your recommendation of a disco valve and screws are based on a 1200psi reg? Is 1200psi what you recommend? In order to achieve 850+ fps with 8.4 grain pellets, how low do you think I can go with the air pressure, maybe with some porting and/or valve work, or other machining? 14+ FPE would be perfect with 8.4 gr pellets, but I surely wouldn't mind getting some 10+ gr pellets up to those velocities as well!
Perhaps there is a walkthrough on getting the extra screws in there? I would think it easier to drill the holes with the valve in the tube, so they are guaranteed to match perfectly. I need to research this. I also hope not to mar the lazer etching that Crosman puts there, but I have to I have to. Maybe I can add a bunch of spaces before my name, “aPpYe” at the CCS, so as to avoid this. Where, in the CCS screenshot below, would the screws go, exactly?
Rsterne: The Almighty Zeus of modern airgunning ... Basically, I plan on doing exactly what you tell me to do!
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I would start with 1200 psi and adjust up or down if you need to, it is only shims required to do that.... and I'm betting you can get what you want at that pressure.... You might hit 14 FPE with less than 1200 psi, but driving 10+ gr. pellets in the mid 800s is about 17 FPE, and I think you will need at least 1200 psi to do that in .177 cal.... OK, maybe you might do it with a Ninja SHP regulator, which is 1100 psi, so if you can find one of those, go for it.... If you can't, get Tim @ Mac1 to build you a 1200 psi setup....
You are going to have to learn to drill accurately to accomplish your goal.... You will need to shorten the front of the 2400 tube to behind the threads, so that you are working with the full thickness tube wall, and then drill that for the two screw holes to install a QB79 style tank block.... You will need to get a Disco valve, which will fit inside the 2400 tube, but it is drilled and tapped for three 8-32 screws, instead of the single 6-40 screw that retains the CO2 valve now.... Do NOT try and do this conversion using a single screw holding the valve, they can come out the back.... At 1200 psi, there is over 500 lbs. pressing on the valve.... If you use the PRod valve screws the hole in the bottom of your tube is the correct size, but you will need to drill two additional holes, one each side, accurately lined up with the holes in the Disco valve, so that all three screws share the load on the valve.... If you don't feel confident that you can drill these holes accurately, then find someone who can....
Bob
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Awesome! I will be ordering my CCS gun before the weekend is up!!! Exciting stuff! I will have to look into the whole drilling thing before I decide whether or not I can do it myself ... I do have a drill press... I guess it is just measuring things and putting the hole in the right spot.
I won't have to do any porting or other machining to get the performance I desire?
I am not sure I follow about the SHP regulators though. Why would they equal 1200psi performance with just 1100psi? Or are the non-SHP regulators not available in 1100psi? This one is throwning me for a little bit of a loop I must admit. For some reason I thought all the ninja regs were SHP.
Also, could you tell me where exactly the screw holes go for the disco valve, in relation to the laser etched engraving? I would like to try and avoid drilling through the letters if I can.
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You likely won't have to do any porting, particularly in .177 cal.... In fact, I wouldn't start hogging things out, you just might lose, not gain, in .177 cal....
The SHP regulators are ONLY available in 1100 psi.... The standard paintball regulators are 850 psi, and use a coil spring, not a Belleville stack.... The Ninja regs. you get from Tim @ Mac1 are available in 1000, 1200, and 1400 psi.... Either 1100 or 1200 should work for you, and you can fine tune them with shims if necessary....
I have never had a 2400 tube, so have no idea where the Laser etching is, and it may vary tube to tube, anyway.... The holes for the valve are on both sides, exactly lined up with the lower screw hole, and at 90* to it on each side.... You will see what I mean when you get a Disco valve in your hand....
Bob
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I have to admit I am almost disappointed in how easy this project will be. I was looking forward to learning some machining skills! So I guess here come the inevitable questions. Drumroll please... What further modifications would be required to get those 14.3 gr .22's to the high 800's? How about heavier pellets? I might just want to cut some metal!
That said, I am admittedly somewhat intimidated by the idea of getting the valve pins in exactly the right place. I did not realize that the holes were already there, and was thinking that i would be drilling the new holes in the hull of the valve at the same time. I guess it would be a matter of measuring exact distance from the end of the tube to the center of the existing bottom hole, then figuring out the 90° from there. That second part is where the intimidation comes in... I did come across a thread where the person didn't feel like lining up the 90° holes, and instead drilled new ones at 120° with the valve in the tube... Any thoughts on this?
Any recommendations on a non-gauge block? Do these also come with pin holes already tapped? :-\
EDIT: Whoops! I did not notice the "pinning the valve" sticky thread. Perhaps I can adapt the same masking tape method... I figure I would mark the tape in the middle where the center hole already is, and put the 90's at exactly .25 "tape lengths" on either side. This would get me the 90, and I figure that I could just measure the length from the edge of the tube to get that dimension. It does seem to me that 120 degrees would be stronger though. Would I thread BOTH the valve and the tube, or just the valve?
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Forget the 120*, use the Disco valve holes.... You can use tape to figure out the position.... If you lack confidence in getting them in the right place, drill them undersize (eg. 1/4") deburr, install the valve with the bottom screw, screw in the side screws (hopefully you didn't get them so far out they won't fit through the 1/4" hole).... Scribe around the head of the screw, and use a Dremel to carefully enlarge the hole until the screw head just goes into it.... You can even work with a round file, a bit at a time.... Take your time, use care, and you should have no problem....
For the tank block screws, Ribbonstone wrote an excellent thread on how to lay out and drill them.... Search for it, or PM him....
If you decide on .22 cal, then you can get more power by increasing the port sizes.... The exhaust port in the valve can be angled towards the seat, the bottom corner rounded, and the diameter increased to at least 5/32".... The transfer port can be drill to 5/32" or 0.161", or you can use a poly port.... The barrel port can also be drilled out to 5/32" or 0.161", even 0.166".... some guys go to 11/64" (0.172") but that is pushing it, you may start damaging pellets on loading.... Making the gun breathe better will increase the FPE at any given pressure.... and of course you can always increase the pressure up to 1400-1500 psi and still not pop the 1.8K burst disc.... Over 30 FPE isn't to hard to get.... My 2260 HPA puts out 37 FPE (18.1 gr. @ 960), 40 shots from 13 CI on 1600 psi.... but uses a full length 2260 tube and reversed tank to take advantage of the larger plenum.... The ports are 0.166" straight through....
(http://i378.photobucket.com/albums/oo221/rsterne/22%20PCP/2260HPA.jpg) (http://s378.photobucket.com/user/rsterne/media/22%20PCP/2260HPA.jpg.html)
Bob
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Huh! Your drilling thing makes a lot of sense to me. I think I can handle that pretty well. I will be looking for the ribbonstone thread you mentioned this evening...
And and look at me back on the .22 bandwagon! I figure that since a heavier pellet will keep its velocity for longer, then I can reach out even further than I could with a lighter pellet. I am hoping for tight groups at 50 yards.
If I want more power down the road, I can always pick up a 2260 tube, or a hipac. I am guessing the hipacs would be less safe though. I have noticed that the HPA bombs (burst tubes, etc) I see here and there seem to share a commonality; they burst at the threads on the end of the tube where it is at its thinnest.
So tank blocks (rather than fittings, nipples, etc) are what I want then. I saw a thread you started back in 2009 about how one can safely modify a standard (from uh ... "bow and arrow shootist" airguns I guess?) qb79 tank block for HPA use. Do you still believe this to be the case? Do you know better alternatives? Any idea what they use on their PCP qb79's? I see big warnings on their site about how one should NOT do this. Would a novice machinist (myself, zero skills at the moment) be able to make one himself? What about the reverse blocks I see here and there? I do like the idea of a reverse tank on a longer tube, but I gather that going the "endcap-to-fittings-to-bottle" route is inherently less safe than going with a block, again due to the threads on the tube making it thinner and weaker ... Thoughts?
Also, I really want to thank you for taking the time to answer my questions as you have been. I have been reading a lot about this stuff these last couple of months and the name handle rsterne has popped up quite a bit with a veritable wealth of excellent information.
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I have used the stock QB79 tank block successfully, and I believe it to be safe with HPA, PROVIDED that the regulator is fitted with a 1.8K burst disc to prevent the tube (and the mounting screws) from ever seeing more pressure than it would with CO2 on hot day (1900 psi at 120*F).... Alternately, for more money, you can get one from JDS Airman that has the screws moved back, further from the end of the tube.... That, in conjunction with high-tensile 8-32 screws, is significantly stronger than the QG79 setup.... although I would still use a 1.8K burst disc.... Staying with a 1.8K disc will limit you to 1400-1500 psi, using more may blow the disc.... Sometimes you can get away with 1600, and sometimes you can't.... When a disc blows, I guarantee you will be looking for a change of shorts.... ::)
Reverse tank blocks are a custom only deal.... and NO I don't make them for sale.... You can do it with fittings, provided you do two things.... 1. use high pressure rated fittings... and 2. make sure you hang the tank securely from the tube, not just on the fittings.... I would advise you not to get too carried away with greed for FPE, because your 2400 tube, after you shorten it to get rid of the threads, will be less than 20cc of plenum.... Trying to push much past 20 FPE will lose efficiency, and may require an increase in regulator setpoint pressure to get back to the power you want....
Bob
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Heh heh. I wasn't gonna ask you to build one, I wouldn't want the liability either! Is it simple enough to make? Would you be willing to provide measurements for your own designs? I just discovered that my neighbor is a pretty accomplished machinist. He has this huge shop! It is something to consider if i choose to go with the 2260 tube at some point.
Going with fittings, aren't I more at risk of failure, due to the fact that I am utilizing the part of the tube that is threaded, and therefore thinner than the non threaded part?
I am not sure I follow about the plenum volume though. Earlier you said that I would have 24 cc "without a gauge block." I took this to mean a block that does not have a port for a pressure gauge. Am I misunderstanding this? Were you mistaken?
EDIT: Aaaand I was up late last night messing with chairgun. The app doesnt have a usable layout on my phone and I kinda gave up on it. I installed it on my tablet and everything lines up! Anyway, it seems that there is only negligible difference between 177 and 22 when it comes to target shooting at 50 yards. Most of the lighter 177s lose a little more velocity and drift a little more in the wind at 50 yards than a 14.3 grain jsb exact, but not by a huge margin. Then I started comparing 10 grain 177s and the differences shrunk to almost nothing. In fact, the 10.3 grain 177 JSB exact heavy has identical BC, POI, velocity and even DRIFT at the target as the 14.3 grain .22 jsb exact, if the chairgun people are to be believed.
How long does it typically take, assuming one knows what he is doing, to change shims around and adjust between 1200 and 1400 psi? Can it be done repeatedly without messing things up? Are the shims like a one time use kind of thing, so each adjustment digs into my pocket a little, and if so, how much? Does the bottle have to be emptied each time?
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The threaded portion of the tube is not pressurized if you build the front adapter correctly, with the O-ring that seals it further back, behind the threads, where the tube is full thickness.... It is critical that the threads not be pressurized, whatever method you use, as they reduce the thickness of the tube by about half....
The "gauge block" I mentioned is like one on a Disco, ahead of the valve, and requiring a hole through the bottom (or side) of the tube.... The (gauge) mounting block, which must be sealed with two additional O-rings (one either side of the hole) is about an inch long, so takes up about 7 cc of volume.... dropping the 24cc down to about 17.... When you use a QB style tank block at the front of the tube, you have to cut off the threaded front portion of the tube, losing about an inch of length, so you still lose volume.... If you had a custom tank block that attached using the threads (like the reversed one on my 2260, that seals inside the threaded portion), you would not lose that volume....
Tank blocks are not very easy to make.... particularly the part that the regulator screws into.... certainly a job for a machine shop.... Here are photos of the reversed block on my 2260....
(http://i378.photobucket.com/albums/oo221/rsterne/22%20PCP/2560Parts2.jpg) (http://s378.photobucket.com/user/rsterne/media/22%20PCP/2560Parts2.jpg.html) (http://i378.photobucket.com/albums/oo221/rsterne/22%20PCP/2560Parts.jpg) (http://s378.photobucket.com/user/rsterne/media/22%20PCP/2560Parts.jpg.html)
That one attaches using the threads at the front of the tube, using a drilled out 2240 CO2 nut, but seals on the full thickness portion behind the threads....
Bob
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I get it, so tensile strength of the threaded section of the tube (and the cap) is plenty capable, so long as they are not also holding back the outward pressure of the compressed air as well. Makes sense to me! This means that a reverse tank is well within my capabilities. The only real advantage I see with a block vs fittings is that the block can support the weight of the bottle by itself. I would still want to support the other side of the bottle though.
Anyway. I think a more powerful .22 will have to wait maybe until next time I decide to undertake a project like this. I think my mind is made up: CCS 2400kt with a 24" .177, peep sight, and a QB block with a 1400psi regulator, likely from mac1. I am going to shoot for 17-18fpe with 10.3 jsb exact heavies or some such... Now I just need to figure out what tank size I want.
I plan on also having an RVA so I can tune for at least a couple different pellet weight classes, starting with the heavies at just below 900fps, some lighter pellets at the same velocity, and a low power setting for closer range plinking and fun with a really high shot count. I will of course tune the higher velocities to the "knee" of the efficiency curve as I have seen you mention so many times!
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Properly tuned, at 17-18 FPE you should be able to get 100 shots from a 13 CI tank.... The bigger you go, the more shots.... but the heavier and longer the tank.... I personally would stay with the commonly available, and cheaper, 13 CI, for your 2400....
Bob
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Properly tuned, at 17-18 FPE you should be able to get 100 shots from a 13 CI tank.... The bigger you go, the more shots.... but the heavier and longer the tank.... I personally would stay with the commonly available, and cheaper, 13 CI, for your 2400....
Bob
The KEY words.
Here's a chart form a member here (Happyhunter) on his reverse bottled .177 QB. Notice the huge difference in efficiency at 16.73FPE vs 17.41FPE - 40% more shots.
AR2078 / 13ci Bottle Reg’d @1375 psi / 10.34 gr JSB / Clipped H-Spring
RVA (turns in 0 1 2 3 4 5 6 7 8 9 9.5
from min preload)
Velocity N/A N/A N/A N/A N/A 179.2 357.1 587.9 731.4 853.5 870.7
FPE N/A N/A N/A N/A N/A .74 2.93 7.94 12.29 16.73 17.41
# Shots N/A N/A N/A N/A N/A 780 510 276 180 108 66
PSI used/shot N/A N/A N/A N/A N/A 1.9 3 5 8 14 23
Shot Count N/A N/A N/A N/A N/A 780 510 276 180 108 66
Efficiency N/A N/A N/A N/A N/A 0.42 1.11 1.62 1.65 1.34 0.85
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That chart is one of the main things that started me down this road a couple of months back! That, rsterne'a $200 PCP thread and a pic I saw of a crosman with a reverse bottle and hollow stock. The shot counts blew me away, as the 15-20 "good shots" on a bell curve (and money) had previously sort of kept me away from PCP's... Here I am now!
That said, I finally pulled the trigger (pun intended) on a CCS 2400kt .177 with a 24" barrel, muzzle brake (are these just for show?) and a Williams peep sight. I am hoping I can get close to those numbers with the smaller plenum...
I am leaning towards a 1400 psi 13/3000, maybe from mac1, and a standard qb79 block. And I need to figure out what pump I want.
I am currently looking into RVA's and HDD's ... Any thoughts/recommendations/advice on those?
I am hoping for some decent accuracy with the crosman barrel... I may even go for a LW or other custom barrel of the accuracy drives me crazy. I am discovering I am a bit of a nut in that department.
I am also fascinated by the idea of building a .22 on the same platform, but with a disco or 2260 tube using a gauge block. Doing this, I would guess I can mount the tank in a "standard" direction, in place of the forestock. Next year maybe. I am also thinking about picking up an a avanti 499 for some indoor BB plinking. One thing at a time though, unless someone feels like throwing money at me. It's the wife's turn to save up for her camera. Why she cares about that when there are guns to be had I haven't the slightest clue. Something's wrong with her...
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I am currently looking into RVA's and HDD's ... Any thoughts/recommendations/advice on those?
RVA? drill and tap the end plug for a 10-32 bolt. Don't really believe in the "HDD's"
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So that is all I would need to do? I am assuming you are saying to do this rather than purchasing an aftermarket rva .. Doesn't the spring need to sit in a recession of sorts? Or is that bolt size enough to push the spring forward?
As for the HDD's, I am seeing that this is something of a controversial (even contentious!) topic. Even the believers report minimal gains. I dunno. I will have to check into it more this evening and decide for myself...
Also, is the stock hammer spring gonna get me the performance I want or should I get something different? Once I decide on a vendor to get my disco valve from (I want to avoid shipping as much as I can by getting things from the same vendor) I will order the rest of my parts.
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So that is all I would need to do? I am assuming you are saying to do this rather than purchasing an aftermarket rva .. Doesn't the spring need to sit in a recession of sorts? Or is that bolt size enough to push the spring forward?
The stock end cap has a hole in it where the spring sits. I take a spent .22 casing and put it inside the spring. This is what the 10-32 bolt will push on.
Also, is the stock hammer spring gonna get me the performance I want or should I get something different? Once I decide on a vendor to get my disco valve from (I want to avoid shipping as much as I can by getting things from the same vendor) I will order the rest of my parts.
Stock hammer will be fine to 1400psi. You will probably have to get a stronger spring. If you search the 22XX HPA posts you should see the springs that different guys are using.
As far as the Disco Valve - I would get that right from Crosman. I think they are about $13. You can also get the springs there. I think the 2100 or 13XX springs are what you want. Get all your part #'s in order and then call them. It will be $4 shipping for everything from there.
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The stock end cap has a hole in it where the spring sits. I take a spent .22 casing and put it inside the spring. This is what the 10-32 bolt will push on.
You just saved me some money!
Stock hammer will be fine to 1400psi. You will probably have to get a stronger spring. If you search the 22XX HPA posts you should see the springs that different guys are using.
As far as the Disco Valve - I would get that right from Crosman. I think they are about $13. You can also get the springs there. I think the 2100 or 13XX springs are what you want. Get all your part #'s in order and then call them. It will be $4 shipping for everything from there.
Except for the block and the regged bottle ... I guess I am going to have to go with at least two different vendors. I haven't looked hard yet, but I think"@rchery airguns" sells odds and ends parts like this as well... I haven't shopped around for a block yet, but they are the only ones I know offhand that has them.
I wonder if Crosman will let me simply add a few items to my existing CCS order...
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Get a "power adjuster" (RVA) from Crosman for the Challenger, it even comes with an appropriate hammer spring.... Heck, you might even get them to install it?.... ::)
Bob
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Hmm. I can get a tap and die set from Harbor Freight for about fifteen bucks. If I do the homemade version with the .22lr casing I can have the satisfaction of having cobbled it together myself... AND it gives me an excuse to go buy some tools!
On the other hand, I do like the knurled head on the bolt in the crosman version. I would assume this means it is easy enough to adjust by hand, without the need for tools, however I do see a "pin" in the Challenger EVP, which I assume is used to hold the adjustment in place... Likely that would need a screwdriver to loosen. How would I hold the adjustment in place with the homemade version anyway? Does the spring tension hold it in place well enough on its own?
It occurs to me that I might want a cross-slide vise to drill all of these holes... This is starting to turn into a slippery slope! I suppose I could manage to clamp things on my drill press...
The power adjuster assembly for sure comes with the spring? I see that they are listed as separate parts, and the assembly on crosman's EVP does not show the spring in the complete assembly.
Also, for the PROD screws (1700-010), I wonder if I need to order three of that part number, or if they come in a set ...
Last, is there much difference between the 1377 spring and the Challenger spring? I guess I would want the one that supports the largest range of adjustment ...
EDIT: Aaaand another question! I keep coming up with these. I am not seeing any of the older style QB79 blocks available, only the new style with FOUR o-rings. This is all well and good, but I was wanting to add another set of screws to the tube and use only the front o-ring on the old style, as rsterne (Bob) has done. The placement of the existing screw holes has me worried, as the grooves cut into the "meat" of the block. I keep imagining myself leaning the gun against a tree to take a leak, it falls over and now I have a torpedo that crushes my legs while I am mid stream and whistling a tune.
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I prefer an RVA with a large screw (3/8") so that you can remove the hammer spring to swap it without having to disassemble the back of the gun.... Unfortnately, even the Challenger RVA doesn't allow that.... Mine came with a spring.... Unless the 1700-001 part number says something like (screw set - 3), then I would order 3 of them.... The Challenger spring is very similar to a Disco spring, so stiffer than a 13XX spring....
I have never used one of the new 4-oring QB blocks.... Given that choice, and the screws still close to the end of the tube.... I would either use it as is (with better screws) and a 1.8K burst disc.... or instead of modifying it use the one from JDS Airman.... more money, but the hole is further from the end of the tube, which is a much better idea....
Bob
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Huh, actually the part numbers for the challenger and discovery springs are identical... So I guess the only question I can think of today is ... What stronger screws? Can I use PROD screws there as well? I was looking at the JDS adapter today and it seems like all they did was purchase the old style block and put holes in it! Do you know if the JDS ones already come with the stronger screws?
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PRod screws will fit the Disco valve.... The heads are smaller, but if you are drilling the tube that doesn't matter.... I think the JDS is drilled and tapped for 8-32 screws, not the Metric ones in the QB.... You would have to ask about the quality he uses, if he even knows or will tell you.... There are only two, so you still should use a 1.8K burst disc for the build....
Bob
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I guess I will make a call tomorrow. I will also try calling “archery guns” to see if they may still have the older style block. The new style makes me kinda nervous.
So I am finally researching regulators and tanks. It seems there are quite a few that are available in the $50-$60 range. In fact, I see standalone 4500psi regulators for under $20... Most, if not all that I have come across on ebay, etc are equipped with 1.8k output side burst discs, and either 4.5k, 5k or 7.5k tank side. These generally come with 800-850 psi output. I see that a lot of people here are going with the ninja brand, but if I can still stay safe, and save some money, I don't mind going generic. Any thoughts on that? Are the burst disc and output pressure adjustment shims generally universal? Are they all adjustable for higher output pressures?
Also, I see that the 3000psi bottles typically come with a 4.5k burst disk, not 3k… I would think this will avoid accidentally bursting the tank side disk because I filled to 3001psi … I will be using a hand pump, and my understanding is that it is pretty grueling to pump past 3000psi anyway. My thinking is that I will rarely even fill to that level anyway, preferring to pump until it starts getting hard, and living with a lower shot count. I don't know honestly, as I have never pumped up a PCP before. In fact, I put a 7 rounds through a disco about 5 months ago, and that is the sum total of my hands on PCP experience!
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Generic Regulators will not necessarily adjust in the same manner as will a Ninja regulator.... Some will have Belleville washers, and others coil springs.... The Ninja 850 psi regs come with a coil spring, you can't adjust them upwards, certainly not over 1000 psi.... To do that you need the SHP regulator, which uses Bellevilles, or you can swap out the coil spring an install Bellevilles.... I have heard reports of some of the imported regulators not holding consistent pressure, which to me means they are not worth the money.... Some don't have two burst discs, and I would NEVER use one without that feature.... The one QB79 I know of that blew up failed because of a cheap reg. with no 1.8K downstream burst disc that bypassed 2600 psi into the gun.... The screws on the tank block sheared off (and the holes nearly pulled out of the end of the tube), sending the tank block / regulator / tank assembly flying across the shop.... Change of shorts required, although nobody was hurt....
The input side burst discs are rated at the Hydrotest pressure, which is 5/3rds the Working pressure of the tank.... A 1.8K CO2 tank uses a 3K burst disc, a 3K HPA tank uses a 5K burst disc, and a 4.5K HPA tank uses a 7.5K burst disc.... If you fill too close to the rating of the disc it will pop, they are only accurate within about 10% (and usually on the low side, for safety).... Repeatedly cycling at near the burst pressure of the disc will fatigue the metal, and eventually it will fail.... The 1.8K discs are intended for the output side of the regulator, and you can usually fill to 1500 psi repeatedly without them failing, but if you use 1600 psi they usually fail after several cycles (and sometime immediately).... Sometimes they will fail on 1500 psi after many cycles, and again, sometimes very quickly.... I have never had one fail with the reg. set at 1400 psi, but have heard of it....
Bob
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So when these discs do fail, is it just a loud bang and rushing air, or will the pressure still send things flying? Also, are the ninja SHP regs the only ones with a disc on both sides that can be adjusted to 1400psi? What about others, say tippmann or gorilla, etc?
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It goes bang, with a VERY loud hissing.... quite startling.... If the gun is sitting near the edge of a bench and the venting is pushing it towards the edge, it may have enough force to knock it off the edge.... Same thing it it's leaning against a bench or table, it may fall over....
Most regulators have two burst discs now, but that wasn't always the case.... I have no experience with Tippman or Gorilla, or any of the Chinese regs. from eBay.... I have only used Ninja, JDS, and RAP4, and they all use Bellevilles except the low-pressure Ninjas....
Bob
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So I see three different price points here then. In your experience, do they all hold consistent pressure? Without that, the whole point of a regulated gun is moot. At the risk of sounding like a pest, have you found any of these three to be more consistent or "better" than the others? I have never been one to jump to the assumption that the most expensive one must be the best ...
Also, assuming I go for the ninja or rap4 (the JDS can just be ordered in the pressure desired), would I also need to purchase additional washers and shims (are these the same thing?) from somewhere to get the 1400psi I am going for? Thanks again...
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Number 1 choice for me would be the Ninja, on a 13CI tank,, purchased from Tim @ Mac1.... He will set the regulator to the pressure you want, and he replaces the factory O-rings with MilSpec which allow the reg. to hold pressure over a narrower range, with longer life.... I think he will set up one with a 1.8K burst disc for 1400 psi, you would have to ask him.... He certainly will for 1200....
Bob
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Hmm. Therein lies a problem. Mac1 is out of stock on the the 13ci combo! The 22ci seems a bit long and/or heavy to me. If I were to get the MAC1 regulator, is it a simple matter to screw it into another tank, say the 13ci or 17ci tanks from rap4? They sell the tanks without the regs.
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Call Tim.... likely he either has some on the way, or will shortly.... All the common paintball tanks use the same threads.... 5/8"-18NF....
Bob
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Okay, so once this check clears, tomorrow should be the big day to order the rest of this gun!
Anyway, I was having trouble deciding what size bottle to get, so I took the time to create a mockup, using vendor measurements I see for the various bottles and regulators. Assuming that Crosman's Custom Shop is reasonably accurate in showing the different barrel lengths, and my math is right, my 24" barreled 2400kt should be just about exactly 42 inches long, and have a nearly SEVENTEEN inch trigger pull!!! That's longer than any of my other guns. I may have to shorten that stock, extend the dovetail back or look for other solutions...
Anyway, having made this mockup, I discovered that I don't think I am gonna like a forward mounted tank with a tank block. That tank is way out there! I am thinking I will go ahead and reverse it. I guess it would all start with the end cap. Are the existing end cap orings away from the threads? Would a Disco end cap with its existing nipple work? Initially, I was thinking to go with a flexible hose and a quick release, as this would allow me to easily remove the tank without having to empty it... As you said, so long as I use fittings that are rated for these pressures, I should be okay, right?
For this idea, I figured I could epoxy some metal to the bottom of the tank, bend it at one end, drill a hole and use the screw that mounts the trigger group into the tube. Of course I am basing this design on the fact that there is a screw in that spot on my 1377, and assuming that the 2400kt has the same trigger frame. Is this the same screw that goes into the bottom of the valve? I could also just send a post into the trigger guard itself, but would rather avoid that...
For mounting the bottle, I was thinking of making something similar to what HappyHunter made here:
http://www.gatewaytoairguns.org/GTA/index.php?topic=81046.msg774493#msg774493 (http://www.gatewaytoairguns.org/GTA/index.php?topic=81046.msg774493#msg774493)
... of course there is always bending hose clamps ...
One of the things that makes me shy away from solid connections (pipes, elbows, etc) is that the tank would have to be supported by a pipe sticking out of the cap, and I don't want to put undue stress on it. Is this a valid concern? I guess rigidly mounting the bottle would take care of that, but then why not go with hoses at that point?
(http://i1066.photobucket.com/albums/u404/appye/13ci%20Mockup.jpg) (http://s1066.photobucket.com/user/appye/media/13ci%20Mockup.jpg.html)
... Any thoughts or recommendations?
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I prefer an RVA with a large screw (3/8") so that you can remove the hammer spring to swap it without having to disassemble the back of the gun.... Unfortnately, even the Challenger RVA doesn't allow that.... Mine came with a spring.... Unless the 1700-001 part number says something like (screw set - 3), then I would order 3 of them.... The Challenger spring is very similar to a Disco spring, so stiffer than a 13XX spring....
I have never used one of the new 4-oring QB blocks.... Given that choice, and the screws still close to the end of the tube.... I would either use it as is (with better screws) and a 1.8K burst disc.... or instead of modifying it use the one from JDS Airman.... more money, but the hole is further from the end of the tube, which is a much better idea....
Bob
All my RVA's are 3/8" with fine threads, just like Bob stated.
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So you just drill and tap a hole in the existing cap yourself then? What about a set screw? Or do you lock it with a nut or something on the end? I would worry about a set screw, because that might mar the threads. I think I can manage to do something like this reasonably well enough. Of course, I can always just buy the Challenger RVA and be done with it!!! Also, I could always drill that one out later on if I am feeling adventurous…
Also, I was thinking about my "quick disconnect" idea ... I see from some other threads that the Discovery fill adapter (Crosman # 1761-101) should thread into the tube as is. I like the idea, but I am wondering if a threaded connection (versus using the fill nipple) might be less prone to leaking... Once the gun is tuned, I doubt I would be needing to depressurize all that often... Also, what is this gonna do to my tube volume?
I see that Mac1 has a steel braided hose that should work well enough for me, I figure 6" would be enough, but maybe I might want to go with the 9" for extra volume?:
http://www.mac1airgunshop.com/braided-stainless-3k-9-p/psibrss.htm (http://www.mac1airgunshop.com/braided-stainless-3k-9-p/psibrss.htm)
Now I just need to figure out what adapters to put on each side...
For mounting the tank, if the epoxy and metal idea isn't gonna work, I can always clamp to the tube in two places...
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I don't think you will be able to bend a hose 180* in that tight a space....
Bob
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Hmm. Hadn't thought of that! What about using a couple of elbows then? What thread am I looking for? 5/8 x 18 unf if I remember right? I could then use a hose between the second elbow and the fill nipple. Would you recommend going with a rigid part there as well?
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I'm personally not crazy about cobbling together fittings to do a job that should be done with a single machined part, but that's just me.... The only thread that is 5/8"-18NF is where the regulator screws into the tank.... The output of the regulator is 1/2"-14 NPS, sealed with an O-ring.... The female threads on the QD fitting are 1/8" NPT.... If you use a standard paintball tank valve (that fits on the 1/2"-14 NPS threads), they usually have a side port, which you could arrange facing upwards, that is 1/8" NPT female threads.... One more elbow and you could have the flow facing back towards the QD, and that could all be done with 1/8" NPT threads, PROVIDING you use high pressure fittings.... Do NOT use brass plumbing or gas-line fittings for this job, only ones rated for at least 3000 psi.... You might need a short hex nipple (double male) in the valve, and then a street "L" (female to male) to get the right height....
Bob
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Hmm. Hadn't thought of that! What about using a couple of elbows then? What thread am I looking for? 5/8 x 18 unf if I remember right? I could then use a hose between the second elbow and the fill nipple. Would you recommend going with a rigid part there as well?
Here is what I did. For your application you could end with a Female QC instead of a 1/8" NPT going in the end cap.
My elbow is rated at 6Kpsi and that brass nipple is rated at 7100PSI. Made by a company named Hoke
(http://www.gatewaytoairguns.org/GTA/index.php?action=dlattach;topic=81046.0;attach=96810;image)
Below is how it wound up. I epoxied a 1/4" alum pin to the bottom of the bottle and drilled a 1/4" hole into the stock. The bottle is very secure. I've taken it off and on several times. Right now I am in the process of putting a .25 barrel on it
(http://www.gatewaytoairguns.org/GTA/index.php?action=dlattach;topic=81046.0;attach=99046;image)
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The output of the regulator is 1/2"-14 NPS, sealed with an O-ring.... The female threads on the QD fitting are 1/8" NPT.... If you use a standard paintball tank valve (that fits on the 1/2"-14 NPS threads), they usually have a side port, which you could arrange facing upwards, that is 1/8" NPT female threads.... One more elbow and you could have the flow facing back towards the QD, and that could all be done with 1/8" NPT threads, PROVIDING you use high pressure fittings.... Do NOT use brass plumbing or gas-line fittings for this job, only ones rated for at least 3000 psi.... You might need a short hex nipple (double male) in the valve, and then a street "L" (female to male) to get the right height....
Would you recommend going with a tube versus the steel braided hose in this case? I was figuring to go with flexible hose because I want to make sure nothing has undue stress on it, and I want to get the bottle as close to the tube, and then as far back as possible. Maybe an extended nipple of sorts?
Also, with this whole avenue of discussion, what am I doing to my overall plenum volume versus the original plan of going with a QB block? I would think it is increasing somewhat, as I would no longer be cutting the tube, and adding tubes and fittings, ASA's etc., although I don't know how far the disco fill adapter goes into the tube, or how thick it is, all in comparison to the QB block.
Here is what I did. For your application you could end with a Female QC instead of a 1/8" NPT going in the end cap.
My elbow is rated at 6Kpsi and that brass nipple is rated at 7100PSI. Made by a company named Hoke
Heh heh ... Okay, so today I have learned a whole lot of new initials! UNF, NPT, NPS, etc. I am not sure what you man by QC... I will definitely look into the Hoke company, although I might want steel fittings (if they are available) since they are going to be sitting out in the world unprotected. If the gun gets knocked over, I want to feel better about the strength of the fittings. Isn't brass pretty soft? Maybe I am being paranoid. Also, for my application, I cannot hang the bottle with the fill cap directly above the ASA like that, as I am using a much shorter tube. This is what had me thinking of going with a steel braided hose and the discovery fill nipple. Check out my mockup below:
(http://i1066.photobucket.com/albums/u404/appye/13ci%20Mockup.jpg) (http://s1066.photobucket.com/user/appye/media/13ci%20Mockup.jpg.html)
Also, I want to mount the bottle as close to the tube as possible, since the bottle will act as the only forestock that the gun will have. That said, I have admired that black gun of yours for some time now! I am really wanting to securely mount the bottle as such so it can act as a solid forestock, and I really like the idea of securing it at the back as you and others have done. Some of this planning might have to wait until I actually have the gun in hand.
If I do this again someday, I might go the route you did, although the QB's are a bit heavy for my tastes, which is what prompted me to order the 2400kt. I hope I don't regret the decision, as there seems to be a general consensus that the QB's tend to have better barrels...
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QC stands for Quick Connect - the female foster fitting. In your diagram you call it a quick release.
Thanks for the compliments on my 78. It's a bit different right now. It's a .25 "Carbine" now. Got a 18" barrel from Roy at MA. I put a Delrin poppet in it and drilled the ports all out to 3/16". I also did a bit more dremel on the valve body. Just shot a 25.4 King and the Chrony said 846. That's 40FPE. Waiting on an LDC from Baxter 'cause it's LOUD.
(http://www.gatewaytoairguns.org/GTA/index.php?action=dlattach;topic=99581.0;attach=141831;image)
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I was thinking that, but I have absorbed so much knowledge today, I was a little bit on overload.
So, when you say I could "end with a Female QC instead of a 1/8" NPT going in the end cap," what you describe isn't quite working out in my head. Especially with an ASA valve, I would think the nipple would at around 28" (on my diagram), and with just an elbow the QC would have to be around 4-5" long! Don't I need a hose or some sort of extended fitting to get the air the rest of the way back?
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what you describe isn't quite working out in my head. Especially with an ASA valve, I would think the nipple would at around 28" (on my diagram), and with just an elbow the QC would have to be around 4-5" long! Don't I need a hose or some sort of extended fitting to get the air the rest of the way back?
From the tank you attach this
(http://chinagreenhill.com/upload/images/%24(KGrHqVHJE!FI!1BJWUVBSCUGlefng~~60_12.JPG)
then you screw the below nipple into it (just like mine looks)
(http://ecx.images-amazon.com/images/I/61u2tbhYQML._SL1215_.jpg)
then screw an elbow like this onto the nipple
(http://g01.a.alicdn.com/kf/HTB1jlVvIXXXXXXxXpXXq6xXFXXXF/-Lead-Free-New-Brass-Pipe-Fitting-Female-90-Deg-1-8-NPT-Elbow-Air-Fuel.jpg_350x350.jpg)
then screw the below long nipple into the elbow
(http://i.ebayimg.com/images/a/(KGrHqR,!lgFC3B2tDF0BQ5d1euSnQ~~/s-l1600.jpg)
finally screw the below QC into the long nipple
(http://ecx.images-amazon.com/images/I/419tvBfYy0L.jpg)
this QC will then attach to your disco fill nipple
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I think you just finalized the design of my gun!
... So what vendors will sell all this stuff at once, without me being a distributor that has to buy them by the lot?
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Sorry, but using a brass pipe nipple like that long one pictured is a BAD idea, unless you can find one rated for the pressures involved.... They are very often thin wall and designed for running an electrical cord through for making a table lamp.... PLEASE be very careful what you use on HPA.... If you can get a very short braided hose, you could use that to make sure there is no mechanical load on the fittings if you fall on the gun, for example....
The Disco fill fitting is about the same length as a QB tank block, but you don't have to shorten the tube to get rid of the threads, so your plenum volume will be slightly larger than with a block....
Bob
Bob
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Sorry, but using a brass pipe nipple like that long one pictured is a BAD idea, unless you can find one rated for the pressures involved.... They are very often thin wall...
I agree 100%, Bob. I could very well be wrong, but the long nipple in that pic looks like one you will find in the plumbing section of any hardware store. BIG difference between those & what you would get from a reputable hydraulic shop and/or supplier.
Case in point - hardware store variety on left & one I picked up from Swagelok on right:
(http://i1100.photobucket.com/albums/g401/windrifle/nptfitting001.jpg)
To be fair though, Rob did state that the nipple he is using is rated for 7100psi so there should be no problems there, although the nipple pictured on his gun is quite different than the last pic…something the OP should keep in mind. Don‘t try and save a few bucks just because Home Depot has a ton of them & they‘re cheap, get the proper ones if going this route & stay safe… ;)
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The nipple on Rob's gun looks like a "Hex Nipple" (like the one in the right in your photo,Todd), and generally of MUCH heavier wall, but even they vary.... I have some (hex nipples) with holes as large as 1/4" or as small as 3/16" (7/32" seems the most common).... The one on the left in your photo looks to be even larger than 1/4" I wouldn't even dream of using it on a CO2 gun....
Bob
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Sorry, but using a brass pipe nipple like that long one pictured is a BAD idea, unless you can find one rated for the pressures involved....
Hoke makes brass 1/8" nipples up to 2.5" they are rated to 7100SPI, they also have SS ones in the same length that are rated to 12,300psi.
Scroll down to the 3rd page in below link.
http://www.hoke.com/pdf/pipe_fitting_catalog_79026_10.12.pdf (http://www.hoke.com/pdf/pipe_fitting_catalog_79026_10.12.pdf)
I was just using those pics so he would get the "picture" of how to put it together. For the long run he could just use a 5K hose with 1/8" npt on both ends.
Ninja makes them like this
(http://www.tippmannpros.com/images/product/large/479_1_.jpg)
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I think the straight flex hose is a better solution than a long, rigid connection.... too much leverage on the threaded portion where it's the weakest....
Bob
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I think the straight flex hose is a better solution than a long, rigid connection.... too much leverage on the threaded portion where it's the weakest....
Bob
If he has to go 4" I agree 100%, especially if the bottle support is questionable.
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Hi All,
Please understand that I am in no way wanting to go cheap with hardware store parts ... I have heard and wholeheartedly understand and agree with the mantra against using plumbing fittings, conduit, etc., and risking your life to save a pretty small amount of money, especially considering the investment into the whole project. While I am a newbie, I am definitely a safety first kind of guy, I have a wife and kids and I don't want one of them getting maimed by an HPA time bomb. I definitely want to go with high pressure rated fittings and I want to make sure this is done as safely as possible. This is what had me initially thinking of going with the braided hose, as I figured it is safer than a rigid connection, allowing the setup to flex if need be.
Now that I have gotten that out of the way, does anyone have experience with the microbore hoses? I noticed them on Mac1 earlier today, BigTinBoat's example of the braided ninja hose sent me to their site, and now I am seeing them again. It's got me thinking. According to Mac1, these are "5000+ PSI" rated. In fact, Ralston Instruments claims that they maintain a working pressure of 6900 psi... They look to be flexible enough to go directly from the ASA to the fill nipple, or even 180 degrees from the reg with the proper ends... This would allow me to bypass elbows and whatnot.
He sells one in 18" (http://www.mac1airgunshop.com/ralston-6900-psi-microbore-hose-p/psimibo.htm) and there is a dropdown that shows a 24" for $5 more. I am wondering if this means he can also make them in custom shorter lengths? I would think I only need maybe 6" or so... Ralston even has a "custom shop (http://www.ralstoninst.com/custom-hose/quicktest/)" of sorts that allows me to design just that. If course, I would probably have to buy a whole pallet of them. It would be cleaner to look at for sure... The idea would be to enclose it in something that would protect from snags and whatnot...
Does all this sound safe to you guys?
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Now that I have gotten that out of the way, does anyone have experience with the microbore hoses? I noticed them on Mac1 earlier today, BigTinBoat's example of the braided ninja hose sent me to their site, and now I am seeing them again. It's got me thinking. According to Mac1, these are "5000+ PSI" rated. In fact, Ralston Instruments claims that they maintain a working pressure of 6900 psi... They look to be flexible enough to go directly from the ASA to the fill nipple, or even 180 degrees from the reg with the proper ends... This would allow me to bypass elbows and whatnot.
I don't think I would put that much bend (to get bottle as close as you want it) in a Microbore hose. From an elbow right to the fil nipple should be fine. I'm sure if you check a local hydraulics shop they could make you one the size you want.
Here is a pic of mine bent to the point where it begins to put pressure on the support spring.
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I'm considering doing this to my 2400kt. There are so many ways to go about it, it can be a little overwhelming. This thread is becoming a wealth of information. I'll be keeping an eye on your build. If it turns out as awesome as I think it will, it should be a good roadmap. Thanks for sharing your project and thanks for all the contributors sharing this great info.
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I don't think I would put that much bend (to get bottle as close as you want it) in a Microbore hose. I'm sure if you check a local hydraulics shop they could make you one the size you want.
You just had to reach over and pop my bubble, didn't you? :-[ I see your point though. Sigh. Okay, I will start shopping around for the fittings today...
I think I will go with a 45 degree street elbow (yeah, I know what a street elbow is now!!!) and the microbore, as it flexes more than the steel braided, making it more forgiving of bottle placement.
I'm considering doing this to my 2400kt. There are so many ways to go about it, it can be a little overwhelming. This thread is becoming a wealth of information. I'll be keeping an eye on your build. If it turns out as awesome as I think it will, it should be a good roadmap. Thanks for sharing your project and thanks for all the contributors sharing this great info.
Check me out becoming a wealth of information! I am right there with you on the whole overwhelming thing ... Two months ago I read rsterne's famous "QB79 Ninja - The $200 PCP (http://www.gatewaytoairguns.org/GTA/index.php?topic=49943.0)" thread and was hooked. I had no idea how to go about things then, but check me out now, debit card in hand and ready to blow some money!
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Okay for the 45 degree elbow, I see this one (https://www.fastenal.com/products/details/424246-131280) from fastenal, this one (http://www.mcmaster.com/#5232t423/=zya99c) from McMaster-Carr, and this one (http://www.grainger.com/product/EATON-AEROQUIP-Adpt-38YN41?s_pp=false&=) from Grainger.
Obviously I like the price of the fastenal one the best, but I am wondering if the male end is too long. I don't want it bottoming out in the ASA...
I like that the one at McMaster-Carr is is of "heavy duty forged or barstock steel construction" and that "the male threads are rolled for extra strength," whatever that means. It does say it operates with a "Maximum psi @ 72° F" of 5,900, whereas the other two say they have a maximum "working pressure" of 5000 psi.
I also have the one from Grainger listed just to keep my options open. It is the most expensive of the three.
I would think any of the three would be good. Do any of you know if the fastenal one is too long, or if the McMaster-Carr pressure rating actually means that the others would likely be higher rated because they use the term "working pressure?"
Am I splitting hairs here?
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Hmm. I just thought of another thing... The disco fill adapter must have a valve in it to prevent air from escaping when you fill the tube, right? Would this valve interfere with regulator efficiency? Meaning is it going to make it so the regulator is less able to keep the psi in as tight of a spread as possible?
Also, the quick disconnect feature really isn't all that important to me, and I worry that it is another source of potential leakage... Does the nipple screw into the cap with the same 1/8" npt thread? If it does, I would think I could just do away with it and screw my hose end directly into the cap...
With this setup, I am thinking that I would also be increasing my plenum volume a little more, as the air would be wide open all the way back to the regulator output. I don't know how narrow the porting is through all of this plumbing, and I also don't know how much these diameters would affect average pressure during the shot with the extra plenum volume...
Maybe I should rethink the microbore and go back to the wider steel hose to further increase volume! I would feel warmer and fuzzier safety-wise with a braided hose anyway. Does this all sound logical, or am I on another hair splitting adventure, ricing my gun at this point?
... and look what I found! 1/8" NPT!!!
(http://img.photobucket.com/albums/v469/DRGreysun/Air%20Guns%20and%20Such/DiscoveryFillNippleDimensionssml.jpg) (http://smg.photobucket.com/user/DRGreysun/media/Air%20Guns%20and%20Such/DiscoveryFillNippleDimensionssml.jpg.html)
Now I am seriously considering this whole steel braided hose directly from my 45 to the tube thing ...
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From the tank you attach this
(http://chinagreenhill.com/upload/images/%24(KGrHqVHJE!FI!1BJWUVBSCUGlefng~~60_12.JPG)
I have to admit, I am having a good amount of trouble finding these things. What are they called? I see a lot of coiled remote lines here and there with similar things attached, but they all seem to be for CO2. Can someone help me? I did find this thing (http://www.amazon.com/gp/product/B0046VNIK8/ref=s9_top_hd_bw_g200_i4?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=merchandised-search-11&pf_rd_r=05V1KDAP2F13QVGHXM70&pf_rd_t=101&pf_rd_p=e268bc31-5c3e-53e2-9383-9355f19afe5c&pf_rd_i=3415691), and it says it is rated for 3000psi, but the reviews are somewhat mediocre, one person talking about how it messed up the pin valve on their tank, etc... It would be nice to be able to turn off the pressure from the tank when I want to dig into the gun at some point...
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From the tank you attach this
(http://chinagreenhill.com/upload/images/%24(KGrHqVHJE!FI!1BJWUVBSCUGlefng~~60_12.JPG)
I have to admit, I am having a good amount of trouble finding these things. What are they called? I see a lot of coiled remote lines here and there with similar things attached, but they all seem to be for CO2. Can someone help me? I did find this thing (http://www.amazon.com/gp/product/B0046VNIK8/ref=s9_top_hd_bw_g200_i4?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=merchandised-search-11&pf_rd_r=05V1KDAP2F13QVGHXM70&pf_rd_t=101&pf_rd_p=e268bc31-5c3e-53e2-9383-9355f19afe5c&pf_rd_i=3415691), and it says it is rated for 3000psi, but the reviews are somewhat mediocre, one person talking about how it messed up the pin valve on their tank, etc... It would be nice to be able to turn off the pressure from the tank when I want to dig into the gun at some point...
They are called ASA on/off CO2 fill valves or a combination of these words. I buy my from "trusted" sellers on Ebay. $10-$12 depending on whether or not you get one with 2 ports (1 for a gauge).
I use the CO2 ones as my regs don't go above 1500PSI.
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The regulator cannot top up the plenum during the shot, it does so between shots.... so flow through the Disco fill fitting is not an issue.... You can remove the check valve for your purposes if you wish....
Bob
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I guess I can go with the co2 ones then... A lot of these are sold with coiled hoses, so I guess I can just discard that part...
As far as the regulator topping up the plenum, that part I was aware of. I was figuring that I might add another cc or two by allowing the plenum to extend through the hose and into the ASA. I am guessing that at some point, the narrowness of this "extension" would have less of an effect on average pressure, say if I had gallons of 1400psi air separated from the tube by a very narrow open port, that extra air isn't gonna be much help during the shot right? This has me thinking, might a regulator be more "accurate," meaning tighter psi range between shots if there was an extremely narrow port between the regulator and the plenum of air it feeds? The idea is that it would top it up in a slower, more controlled fashion.
Anyway, I don't really even know how regulators work in the first place, just tossing around some newbie theory! I just know that they are these magic things that use shims or springs ("wing of bat" or "eye of newt") of some sort that adjust the magic.
What kind of psi range do regulators typically achieve shot to shot anyway? Bob mentioned that the delrin o-rings that mac1 puts into the ninja regs he sells create a tighter psi range ... how much tighter? BTW, I finally called him, but only got voicemail. I am gonna get a 6" braided steel hose and a ninja reg from him. I would like to get the whole regged tank (13ci) package from him, but I don't know if that is gonna happen until I talk to him. If he doesn't have the tank, I can always get the bare tank from rap4...
Also, does anyone have any opinions on the street elbows I mentioned a few posts ago?
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Ninja regulators hold a shot-to-shot pressure variation that you can't see a difference on a gauge that has 50 psi increments, so that would be less than 10 psi.... From a full tank down to 1000 psi, however, they might drop up to 50 psi.... If your gun is tuned to the "knee", which means near the peak of the velocity curve, that 50 psi won't cause any measureable change in velocity, however.... Just the variation in pellet weight and fit in the barrel has a greater effect on velocity than regulator output variation in a properly tuned gun.... IMO, have a tiny hole between the regulator and plenum is probably the wrong way to go, regulators work better if the pressure can come up to the setpoint rather quickly.... although to be truthful I have never seen that to make any difference with a Ninja reg. but it has been reported with some brands of "in-tube" regs....
Bob
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heh heh ... that's what I get for theorizing on something I had no idea about! It makes sense that pellet variation would likely have a pronounced effect. I often find myself checking pellets before every shot, especially for skirts that are out of round. I think I am gonna take some time to learn about these regulators...
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Okay, I get the basics of how they. Simple enough. In Wikipedia's example (https://en.wikipedia.org/wiki/Pressure_regulator), Inlet pressure, combined with outlet pressure on a diaphragm overcomes spring tension, keeping a valve closed. When outlet pressure drops, spring overcomes the combined pressure on the diaphram and opens the valve, allowing more pressure to enter the outlet side, which pushes on the diaphragm, closing the spring again. I think i got this right.
So in the case of the ninja reg, I am guessing the concept is the same, but using a stack of shims to provide spring pressure ... I did find this drawing (http://www.zdspb.com/media/cadfilepost/ydna/tankreg/thumb/ninja_prov2_tankreg_assembly2.jpg), but I am not sure what I am looking at honestly, or how similar it is to a ninja reg. The valve looks to be in its closed position, and I recognize the shims, but I don't know what the pink thing in the middle, or the blue circle at the top.
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Also, I am trying to decide how long I want my braided steel cable. Based on my mockup drawing, I figure 6" would be about right, but does anyone know how accurate my measurements are here? All I had to go on was the CCS graphics where you choose barrel sizes. In a photo editor, layered the various barrel length guns pixel-perfect on top of each other, did a little arithmetic based on what pixels the 18" and 24" barrels ended at and came up with the ruler in my pic. The 10.1" and 14.6" barrels seemed to fall in line just about perfectly, so I figured all was correct. Each red line is supposed to be exactly one inch apart in the drawing...
Here is the latest version of my mockup:
(http://i1066.photobucket.com/albums/u404/appye/13ci%20Mockup%202.jpg) (http://s1066.photobucket.com/user/appye/media/13ci%20Mockup%202.jpg.html)
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So in the case of the ninja reg, I am guessing the concept is the same, but using a stack of shims to provide spring pressure ... I did find this drawing (http://www.zdspb.com/media/cadfilepost/ydna/tankreg/thumb/ninja_prov2_tankreg_assembly2.jpg), but I am not sure what I am looking at honestly, or how similar it is to a ninja reg. The valve looks to be in its closed position, and I recognize the shims, but I don't know what the pink thing in the middle, or the blue circle at the top.
(http://www.zdspb.com/media/cadfilepost/ydna/tankreg/thumb/ninja_prov2_tankreg_assembly2.jpg)
This is just like the Ninja SHP reg. The pink thing keep the air in the bottle when reg pressure is reached, the blue thing keeps the air in the reg when nothing is attached to it.
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Aaaaah now it all makes sense! So the air goes into those ports next to the "pink thing" and causes the piston to go down and compress the bellvilles...
Anyway ALL PARTS HAVE BEEN ORDERED!!! I am going to be down in the Los Angeles area for the thanksgiving weekend so I will be stopping by Mac1 personally to pick up my regulated tank, braided line and benjamin pump!
Hopefully the gun arrives soon so I can start drilling holes and violating it!
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Also, I am trying to decide how long I want my braided steel cable. Based on my mockup drawing, I figure 6" would be about right, but does anyone know how accurate my measurements are here? All I had to go on was the CCS graphics where you choose barrel sizes. In a photo editor, layered the various barrel length guns pixel-perfect on top of each other, did a little arithmetic based on what pixels the 18" and 24" barrels ended at and came up with the ruler in my pic. The 10.1" and 14.6" barrels seemed to fall in line just about perfectly, so I figured all was correct. Each red line is supposed to be exactly one inch apart in the drawing...
Here is the latest version of my mockup:
(http://i1066.photobucket.com/albums/u404/appye/13ci%20Mockup%202.jpg) (http://s1066.photobucket.com/user/appye/media/13ci%20Mockup%202.jpg.html)
Hi Patrick,
Don’t know if this helps or not, but I had an extra 13CI bottle laying around doing nothing along with a remote coil hose (just needed the ASA on/off valve, but didn’t feel like taking it apart for the pic) and my old 2250, so did a quick mock-up to give you a reference for your measurements.
Bottom of bottle is flush with forestock mounting tab, barrel is 14”. If you used a “street” elbow in ASA on/off valve, you’d be looking at around 4.5” - 4.75” for your braided line with that configuration.
(http://i1100.photobucket.com/albums/g401/windrifle/1750%20PCP%20Target%20Pistol/m_2250%20hpa%20005_zps37vsasrp.jpg)
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Hey man, thanks for taking the time to do that! I was able to lay your pic right on top of mine almost seamlessly and the rulers matched up, so it looks like Crosman's graphic is pretty much spot on.
...What is the green thing between the regulator and the ASA?
The idea I have been rolling with for the last day or so has been to do away with the fill nipple and send the hose fitting directly into the fill housing. With this configuration I was thinking I would go with 5-6" to the elbow... I initially thought of going this route to eliminate a potential source of leaking... Anyone have experience with having quick disconnect fittings connected long term?
The other thought was that this extends the plenum by a few nosehairs by eliminating the check valve and having open air down into the asa. Anyone have any ideas on how many nosehairs I am gaining here? A little more power is always fun...
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So I ordered this ASA (http://www.ebay.com/itm/281843745872) off of ebay earlier today. It seemed as good as any ...
(http://i.ebayimg.com/images/g/6a8AAOSwo0JWIKMS/s-l500.jpg)
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So I ordered this ASA (http://www.ebay.com/itm/281843745872) off of ebay earlier today. It seemed as good as any ...
(http://i.ebayimg.com/images/g/6a8AAOSwo0JWIKMS/s-l500.jpg)
yep, that was the american made one with the degrasser built in, right?
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...What is the green thing between the regulator and the ASA?
That would be the bonnet that houses all the reg internals - pin valve, piston, springs, shims etc, etc...that's the part you need to remove in order to service the reg or adjust output pressure.
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Oooh I see. I wasn't paying attention, the bonnet is just a different color on that reg... I was thinking it was some other attachment between the regulator and the asa.
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Bob, there is something wrong with your website... I see no mention of the word "airgun," "reguator," "barrel," "caliber," or even "pellet!" Although I see a nice looking crosman in one of your hunting pictures... Even without an "airsonal" museum, your inn looks like a really nice place to stay!
Anyway have a happy Thanksgiving everyone! Or I guess as Canadians might say, "Enjoy your Thursday, Thanksgiving was six weeks ago!"
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*LOL*.... my wife loved the "six weeks ago" comment.... I think if we up here in the Frozen North waited until late November, the Turkeys would have all been eaten by Coyotes!....
Bob
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Up here we get an occasional dusting, according to people in town anyway. As a matter of fact, we just got snow yesterday for the first time since we bought the house last year! I hope we don't get snow that sticks for long periods... I grew up in Los Angeles, my daughter never even saw snow before. Speaking of which, it's time for that four hour drive now...
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So I now have my bottle, pump, some 90 durometer orings to replace what I will get with the disco valve and fill adapter, and an extended probe to replace the stubby thing that comes with the 2400kt. At least I think the 2400kt comes with the same one that goes in my 1377. Tim at Mac1 mentioned to me that this gets you better accuracy because the pellet is already square in the rifling when the air starts pushing it forward, rather than still sitting somewhat in the leade and being slammed into the rifling at whatever angle it wants. At least that is how I understood it...
I saw one person on youtube who made an extended probe using a piece of bailing wire and some drilling ... I might try that on my 1377.
Tim did not want to set my reg to 1400psi with a 1.8k burst disk, so he went with 1250. It currently has a 5k disk on both sides because he did not want to burst disks while he was adjusting pressures. I almost walked out of there with it like that! He gave me a 1.8k and a 3k, along with some shims to play around with things if I want. Once I get my ASA (so I can use something a little more "proper" to depress the ball and degas), I will be installing the 1.8k disk on the output side. I think I will see what I can get out of the 1250psi setting before I start messing with shims ... or maybe I won't! I am gonna have to learn about shims and bellvilles now ... I figure someone here must speak ()()()()(||||?
I also gotta say, Tim at Mac1 is a pretty cool guy! Fiesty as *(&^, but he really went the extra mile to make sure I was set up well, explaining things as he went along. I was in his shop for a good hour and a half and he spent a lot of time explaining things to me. Not only that, but I my newly steroided silver streak back from him about a month ago that I was having accuracy problems with, and he cut a nip off of the end of the barrel and recrowned it for me free of charge! Of course, I did spend almost $400 in his shop that day ... Today is test day for that thing. I am driving back up north tomorrow, so it has to be today, or else I will have to wait for Christmas to get it back to him again if it still shoots shotgun patterns at 20 yards. I hope my parent's are gonna be cool with me popping off a few groups in their suburban (well, they still have an acre) yard! Streaks are not known for their diminutive voices...
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Hi All,
Before I start building this thing, I figured I would find out from all of you what your experience is with the desiccant filters I see online. I picked up a Benjamin pump.
Here is an example:
http://www.amazon.com/Sun-Optics-USA-Desiccant-Pressure/dp/B0094O3GZE (http://www.amazon.com/Sun-Optics-USA-Desiccant-Pressure/dp/B0094O3GZE)
I see this home made one here as well... It seems like it would work... I guess I will be spending the drive home reading about the different silica gels...
(http://i202.photobucket.com/albums/aa86/madmike77_photos/Airgun%20Stuff/IMG_3646_zps1c501a6a.jpg) (http://s202.photobucket.com/user/madmike77_photos/media/Airgun%20Stuff/IMG_3646_zps1c501a6a.jpg.html)
Is this all snake oil, or do they actually work? I know I don't want my gun to rot out from the inside.
... How often should I expect to be tearing things down as a maintenance cycle?
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Okay! I put my pump together, pumped the bottle to 3000psi and figured they were in good working order. Tim built my reg with 1250psi output and a 5k disk on both sides. He also gave me two really thin shims and one thicker one. After emptying the bottle, I threw all of them at it and pumped it up. After reaching over 1600psi (and climbing) on the reg tester I put together, I emptied everything and took the thick shim out. This got me right where I want to be. I saw that the reg tester hovered right at 1400psi when the bottle and pump gauges read 1700psi. I continued all the way up to 3000psi and saw that the reg read 1450psi. As I understand things, this amount of "creep" is normal. I again emptied the bottle and installed the 1.8k disk on the output side, replacing the 5k Tim had on there initially. I pumped all the way up to 3000 psi and the disk is holding 1450psi.
...At least it didn't burst. I do hear some air coming out of there now... I hope I did not install it too tight or something. I hand tightened it and gave it maybe a quarter to half a turn more, I don't remember. I wrapped white teflon tape around the threads two times... The sound does seem to be coming from the two holes on the side of the disk housing though. Do burst disks ever just leak slowly like that? Don't they normally either stay solid or burst suddenly? Maybe it is defective? Tim did not test it while I was there...
I will take it apart tomorrow and try again. I pumped that thing up four times over the course of about an hour and I am tired!
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...At least it didn't burst. I do hear some air coming out of there now... I hope I did not install it too tight or something. I hand tightened it and gave it maybe a quarter to half a turn more, I don't remember. I wrapped white teflon tape around the threads two times... The sound does seem to be coming from the two holes on the side of the disk housing though. Do burst disks ever just leak slowly like that? Don't they normally either stay solid or burst suddenly? Maybe it is defective? Tim did not test it while I was there...
I will take it apart tomorrow and try again. I pumped that thing up four times over the course of about an hour and I am tired!
Sounds like it's leaking. I would take the tape off the threads as they do not seal. The copper colored "disc" on the end of the threads is what seals against the face of the regulator. I give mine a little torque with a socket. You should not hear any air coming out.......until it bursts.
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You don't use Teflon tape on a burst disc, it has straight thread (not tapered pipe thread) and seals against the shoulder on the bottom of the hole with the copper disc, as noted....
Bob
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Okay, I will remove the teflon... How much torque do you normally apply?
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Okay, I will remove the teflon... How much torque do you normally apply?
Never even had anything to measure with, but I would say I tighten a little less then I do for spark plugs.
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Okay. I was a little scared to overtighten. What materials are in play here anyway?
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Okay. I was a little scared to overtighten. What materials are in play here anyway?
Alum bonnet and brass or bronze disc I would say
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Okay I THINK I got the disk squared away... I don't hear any hissing coming from there anyway. It is hard to tell for sure because now I am getting a leak passed the ball valve!!! Do the Bellville stack and the piston pull out as an assembly, as I have seen on some YouTube videos? I am wanting to get a closer look at what is going on with the little gasket. I have a ninja pcp regulator with a sort of copper colored base, and the bonnet is marked "1400 PSI OUTPUT" ...
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Soapy water is the best for checking leaks.... There are no "gaskets" in a regulator, just O-rings, and the ball shaped seal on the end of the piston....
Bob
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Well the little green print that the ball seals against then...
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sigh. I need to stop using my phone on this forum. I was referring to the little green oring that is in between the ball and the housing.
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sigh. I need to stop using my phone on this forum. I was referring to the little green oring that is in between the ball and the housing.
Autocorrect passes me of.
Steve
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Okay, I took the bonnet apart and reseated the little square edged oring that the steel ball sits against. I liberally applied silicone grease to all seals, put it together and pumped it up. It seems all leaks are squared away. That square edged oring was the only oring that was not of the white 90 durometer variety. Perhaps Tim forgot to upgrade that one? It was sort of spread around the hole so the ball was pressing metal to metal against the housing.
Could this have been caused by me letting the air out too quickly or incorrectly somehow? Is there a proper method to degassing the bottle?
Anyway, it sits in the spare room at exactly 3000psi, according to the ninja gauge... We shall see if it is still sitting there tomorrow morning. I am thinking it might not be a bad idea to retest the output pressure as well, since I did remove the stack and put it back in...
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the little square edged oring that the steel ball sits against.
Must be a different Ninja regulator than any of mine.... All the ones I have use the brass pin valve sitting on a Delrin seat that looks like a conventional (round section)O-ring on the outlet side of the bonnet....
Bob
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the little square edged oring that the steel ball sits against.
Must be a different Ninja regulator than any of mine.... All the ones I have use the brass pin valve sitting on a Delrin seat that looks like a conventional (round section)O-ring on the outlet side of the bonnet....
Bob
The "newer" ninja's do have a "ball", not a pin. I've got some of each
(http://www.paint-xtreme.com/pxshop/images/product_images/info_images/4672_0.jpg)
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I've seen that.... don't have any, never had one apart.... Is that part of the system to insure that HP regulators can't be used on paintball guns?....
Bob
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I've seen that.... don't have any, never had one apart.... Is that part of the system to insure that HP regulators can't be used on paintball guns?....
Bob
No, it is the regular paintball one, this is the PCP one......valve is much deeper in bonnet
(http://www.punisherspb.com/Images/Ninja-Paintball-Products/2015/pcp-tank-reg/PCP3K-Reg-stand-X2-lg.jpg)
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Hmm. Here are some pics of mine. As you can see there is no recession like the one in the previous post. Maybe it is because it is the "1400psi output" model ...
(http://i1066.photobucket.com/albums/u404/appye/IMG_0008.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0008.jpg.html)
(http://i1066.photobucket.com/albums/u404/appye/IMG_0009.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0009.jpg.html)
(http://i1066.photobucket.com/albums/u404/appye/IMG_0010.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0010.jpg.html)
(http://i1066.photobucket.com/albums/u404/appye/IMG_0011.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0011.jpg.html)
Here is a picture of the ball removed with the little oring, you can see a slight deformity in the oring itself. This is the one I am wondering if Tim forgot to replace...
(http://i1066.photobucket.com/albums/u404/appye/IMG_0005.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0005.jpg.html)
This morning I woke up to see that it had lost about 250 lbs, according to the ninja gauge. I used soapy water to see that the seal was completely solid at the ball valve, and that there was a very slow leak at the 1.8k disk once again. I took it out and saw that an eylash (nosehair?) had fallen down in there and was likely the culprit. I added a thin film of silicone grease to the mating surface (the cup?) of the disk and reinstalled. It is now sitting at 2500psi, because the line is thinner, and I will more readily recognize needle movement against it. I don't see any bubbles coming up with the soapy water, so hopefully we are good this time. I will let it sit like that and see how it looks tomorrow.
Man! Keeping this stuff sealed is no joke! I may need to get me a lab coat...
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"Your Crosman order has shipped!"
Oh happy day!!!
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Sigh... Still leaking. How many times can I remove and replace a burst disk before it is ruined? Maybe I shouldn't have used the grease? I dunno... It could very well be leaking elsewhere. I just saw that it has already lost a couple hundred pounds in as many hours...
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Hmm. I seem to remember that temperature does have some minimal effect on pressure... I think maybe I am seeing this. I filled to just a nosehair above 2500psi at around 11am today, and noticed by about 12:30 that the pressure had dropped to maybe 2400psi. I went all day thinking that I would have to take things down and inspect for eylashes and nosehairs yet again. Now, at 7:13pm, I am seeing that the needle has not moved at all since 12:30. I am guessing this is to be expected?
EDIT: All right! I see references to "slam filling" and other terms used that describe this very thing. The tank gets warm after an initial fill, and the pressure is found to be decreased some hours later. I am guessing the friction of all the air particles being closer together and whacking (that's a scientific term, by the way!) against one another creates heat, but once all the all that high pressure whacking, smacking, bashing, swirling, hitting, tomfoolery and general shenanigans settles down, the temperature, and corresponding pressure, drops slightly! Yeah, I am getting me a lab coat for sure!
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Actually, now that I think about it, when initially pumping up a tank, you are taking a large volume of air that contains an amount of heat and compressing that air, along with at least some portion of its retained heat. When room temperature air is continually compressed into the tank the temperature will continue to rise because you are taking a large volume of warmer air and putting it into a smaller space. I would imagine this increase in heat rises by some mathematical number in relation to the speed at which it is compressed. This compression is what causes the heat to rise in a diesel engine cylinder, allowing the fuel to combust, which is similar to what happens when a springer "diesels"...
I am pretty sure I have read somewhere that there are those who have attempted to take advantage of this to increase velocity... I gotta read on whatever results people have had... I wonder if it can be reproduced with a level of consistency that would allow for consistent fps. I am sure someone has tried... On to google!
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Okay, so in playing around with pressures, and being really happy with the fact that I did not have any leaks, I figured I would go with a full bottle. I started by going up to about 3100psi in my living room which was 69 degrees, according to the thermostat. Putting it in the cold guest room brought it back down just below 3000 psi and bringing it back in the living room got it back to 3100. I even put it in the freezer and saw the pressure drop down to about 2600psi. After sitting in the living room again for about an hour it was back to 3100, so I thought I would see how high the pressure would go on a hot day. I started by holding the bottle under my arm pit for a while and was able to get the pressure to rise to about 3400psi or so.
... Then I was holding it in my hand and watching TV and the 1.8k disk blew! I am thinking that while the bottle was in the freezer, regulator pressure also dropped and allowed more air into the outlet side. When the temperature rose back up, this additional air brought the outlet side to whatever increased pressure finally blew the disk. Maybe it has something to do with the fact that I calibrated the regulator to 1450psi with 3000psi in the bottle while I was in my garage that was probably about 50 degrees. Not sure about that one...
I ordered a two pack of 1.8k disks off of ebay for 3.95 with free shipping. Not bad!
Anyway, I am going to put the 5k back in there and see what these temperature variations do to output pressure.
Speaking of that, I may have to rethink my whole 45 degree fitting idea. I did not realize how little thread is actually engaged when using NPT... The female end of that fitting is going to be sitting much higher than I originally thought! I kind of wish we could use straight thread everywhere instead ... it seems superior to me, especially since it does not rely on deforming the threads to make a seal. I would think npt threads would be much less reusable. Oh well, maybe that could be a project for another day. Or I could just buy new fittings every once in a while...
...aaaand I am done rambling.
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Yep, confirmed. I filled to 3100psi in my living room and saw somewhere between 1425psi and 1450psi on the reg tester. I put it in the freezer for an hour or so and saw bottle pressure was down to about 2600psi, while the output pressure remained unchanged. Now that the assembly has been removed from the freezer for about 30 minutes, I am seeing 1650psi on the output side and it is still cold in my hand. Bottle pressure still shows about 2900psi so I would think we will still see some pressure increase.
I guess this means that it would be a good idea to let some pressure out of the gun after bringing it into the house, if I am going to continue to have the regulator set this close to the 1.8k burst pressure I plan on having on the gun.
... Since the gun will likely arrive before the new burst disks, I will be keeping things under 2000psi while doing my initial tuning and whatnot, as I like my arms and legs intact. I figure I can at least get a lower resolution idea of where the gun is tuned based on RVA turns... I figure I will be looking at a single 500psi increment (2000psi down to 1500psi) on the ninja gauge, rather than seeing performance over the broader spectrum of a full bottle fill.
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As the tank cooled, it let a bit more air into the bonnet to maintain 1450 psi.... then when it warmed up, that air expanded and increased to 1650.... This can cause a marginal burst disc to fail, but is not an indication of a regulator problem, and is to be expected....
When tuning the RVA, you should find that above a certain preload you get no further increase in velocity.... Tune for the point where the velocity just starts to drop for the most power with efficiency.... If you want less power, then decrease from there.... but be advised that if you drop down very much, the velocity will INCREASE when the pressure drops below the setpoint of the regulator.... just like in an unregulated gun (velocity increases initially as pressure drops)....
Bob
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I am thinking this will not be much of a problem here, as it rarely gets below freezing here before 3am, and even the colder daylight hours generally rise pretty quickly above 50(F) here in the winter ...
I figure I will still occasionally dry fire the gun if I haven't fired it after some time, that is if I ever recover from this airgun frenzy I am hopelessly addicted to at the moment!
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Heh heh ... yeah, I am seeing about 1725psi on that thing now that it has been out of the freezer for some hours... No wonder the disk burst.
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Not sure how I feel about this ball valve design. A coil spring holds the ball up when there is no pressure in the bottle. This has happened to me a few times now when I evacuate... Twice I have had this issue, and one time, the oring wasn't even off center like this, the ball pushed into the oring hard enough to stretch it to the side... I have to remove the bonnet, pull the stack and reseat the ball, spring and gasket to fix things...
(http://i1066.photobucket.com/albums/u404/appye/IMG_0059.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0059.jpg.html)(http://i1066.photobucket.com/albums/u404/appye/IMG_0060.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0060.jpg.html)
...I am thinking of using this silicone goop to keep the oring in place, maybe even using it instead of the oring. I dunno ...
(http://i1066.photobucket.com/albums/u404/appye/IMG_0062.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0062.jpg.html)
sigh.
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Post those photos in the Ninja gate and have Ray comment....
Bob
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Not sure how I feel about this ball valve design. A coil spring holds the ball up when there is no pressure in the bottle. This has happened to me a few times now when I evacuate...
I think you may be "Evacuating" too quickly. This cools the seals to a point that they are distorting.
Also with your pressure going up to over 1700 it sounds to me like you are getting regulator creep. I've had 2 of my bottle at 1500 for a few months now and the reverse bottle gun has a gauge between the gun and tank. Never has it gone up over 50psi between temperature changes.
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sigh. I need to stop using my phone on this forum. I was referring to the little green oring that is in between the ball and the housing.
Autocorrect passes me of.
Steve
;D ;D ;D
Passes me of two.
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Post those photos in the Ninja gate and have Ray comment....
Okay, will do... This keeps happening! I am not sure if the oring is too soft or what ...
I think you may be "Evacuating" too quickly. This cools the seals to a point that they are distorting.
Also with your pressure going up to over 1700 it sounds to me like you are getting regulator creep. I've had 2 of my bottle at 1500 for a few months now and the reverse bottle gun has a gauge between the gun and tank. Never has it gone up over 50psi between temperature changes.
Initially, I did evacuate (is there a proper term for this?) rather quickly, and I ran into the distorted oring, so the problem may well be due to the oring having become distorted in the first place. What I have been running into probably about 5 times now is definitely not because of evacuating too quickly. I have an ASA attached that has a built in degasser, so I SHOULD be able to back out the pin and it evacuates the gun but not the bottle. This usually works about three or four times before the oring is once again out of place. Then I once again have to pull the bonnet apart and reseat the oring. Very frustrating. I am at this point wondering if it is possible to just get the standard pin and replace the ball design with that.
As for the regulator creep, I am thinking that this is not what happened. I am able to reproduce the effect reliably by dropping the temperature and bringing it back up again. I actually saw the pressure rise well above 1700 when I left the bottle in the freezer for several hours, then looked at it the next day after it warmed up again. If the regulator was "creeping" I would see the pressure rising regardless of temperature, correct? I am not seeing that happen, as I have seen it hold pressure for several days so far...
Anyway, I got my gun last night and tore into it right away! I pretty much got it all together now, except I am gonna have to run into town tomorrow to get a 90 degree fitting and maybe shorten my hose or buy a shorter hose... The 45 certainly doesn't work as I had originally thought it would. The gun sure sounds impressive when I dry fire it though! With the 24 inch barrel, it sounds much bassier than my silver streak, which has a higher pitched crack. It is actually quite a bit quieter. I have yet to send a pellet through it...
I also screwed up with my valve pin locations. One of them was ridiculously off center! If I do this again, next time I will start with MUCH smaller holes so I can see where I am as I get the dremel and start enlarging them. After a few expletives and some careful grinding, this is the hack job I have now. Feel free to chuckle:
(http://i1066.photobucket.com/albums/u404/appye/IMG_0124.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0124.jpg.html)
(http://i1066.photobucket.com/albums/u404/appye/IMG_0123.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0123.jpg.html)
(http://i1066.photobucket.com/albums/u404/appye/IMG_0125.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0125.jpg.html)
I actually had to make the factory valve pin hole a little oblong in order to make them all match up as well as I could. I figure oblong doesn't really matter since we are only dealing with pressure in one direction... I made them all match up at the rear of the gun as best I could.
Of course, now my transfer port is slightly off center. I am not sure if I am gonna be able to do anything about that...
(http://i1066.photobucket.com/albums/u404/appye/IMG_0126.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0126.jpg.html)
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Hard to tell from the orientation of the photos, but if all three screws are resting against the rear of the holes it should be safe enough.... but a closer fit would be better, of course....
If you enlarge the exhaust and transfer ports, just work on the front of the exhaust port with a Dremel to re-center it in the hole....
Bob
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Okay, so the exhaust port is the hole in the valve and the transfer port is the hole in the tube, correct? This leaves the sleeve and the face seal (according to Crosman's EVP for the Disco (https://support.crosman.com/hc/en-us/article_attachments/202462020/BP1K77xx_and_BP9M22xx_EVP.pdf))...
I would actually like to push things rearward a tiny bit more, because the screw that is going through the word, "warning" is not quite sitting against the tube. I got a little overzealous with the dremel.
If I enlarge the exhaust and transfer ports, wouldn't I also need a larger sleeve and face seal?
What kind of performance deficit am I looking at if I leave it off center? I had thought about enlarging the holes yesterday but I remembered you told me earlier that going with larger porting might actually cause me to lose performance in .177 ...
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The transfer port is the metal sleeve and it's associated rubber seal.... It is the piece that transfers the air from the valve to the barrel.... The exhaust port is the hole in the valve facing upwards.... Below that, facing forwards, is the throat.... The hole in the barrel is the barrel port....
I forgot you were doing .177.... probably no need to make anything larger, a slight amount of misalignment probably won't make any difference.... I've seen ports out that far in a new gun....
Bob
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Actually, now that I think about it, when initially pumping up a tank, you are taking a large volume of air that contains an amount of heat and compressing that air, along with at least some portion of its retained heat. When room temperature air is continually compressed into the tank the temperature will continue to rise because you are taking a large volume of warmer air and putting it into a smaller space. I would imagine this increase in heat rises by some mathematical number in relation to the speed at which it is compressed. This compression is what causes the heat to rise in a diesel engine cylinder, allowing the fuel to combust, which is similar to what happens when a springer "diesels"...
I am pretty sure I have read somewhere that there are those who have attempted to take advantage of this to increase velocity... I gotta read on whatever results people have had... I wonder if it can be reproduced with a level of consistency that would allow for consistent fps. I am sure someone has tried... On to google!
;D Yes the same principal applies to air conditioning and refrigeration and the heat is moved to somewhere you don't care about. With the air bottles that is not an option unless you put it in an ice chest and cool it down as you fill but then you could easily over fill the tank
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So my 45degree fitting idea was a bust! I did not know that npt fittings typically leave a lot of thread showing. The resulting fit had the hose rammed up against the barrel, or the bottle hanging way off of the tube. Really ugly! Oh well, I am sure I will find a use for the fitting down the road... I put a 90 degree street elbow on there and the bottle now goes flush with the tube nicely. Of course I think I am gonna have to head back to the Parker store and get a pipe nipple and regular 90degree female-female elbow, as the fill nipple on the bottle doesn't quite clear the threaded hose... Maybe just a small female to male nipple, if such a thing is readily available...
Anyway, I am trying to figure out if I want the bottle right up against the tube or against the barrel band. Any thoughts on floating the barrel (removing the barrel band) with this gun? I figure I would want to put in another couple of set screws (at 120 degrees) if I were to do so... I suppose I could even set it with four screws...
Also, I am a big boy now! I couldn't get any of my tablet or smartphone chronograph apps to agree on a reading so I picked up a real chronograph. I went with the Caldwell because it was cheaper at my local sportsmans warehouse... The concept of these auditory chronographs seems to make sense, but likely I would need to be in a large field or on a mountaintop somewhere with no echo... Oh well.
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Beuller?
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Congrats on moving up to real tinkerer/tuner status with your new chrono!
I don't think free floating the barrel will cause any problems.
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Hmmm. So I am thinking my I might have to clip the hammer spring or something. With 1450psi reg pressure and a few turns in on the RVA, the gun averages maybe 925fps (I need to verify this) with the 10.34gr JSB heavies... However, with any of the lighter pellets, they all start at over 900fps with the RVA turned all the way out, and accuracy is suffering.
... I am trying to decide if lowering the pressure or clipping the spring would be the right way to go. I wouldn't mind lowering the max FPS with the JSB heavies to maybe 875 or so, but I want that velocity to be as efficient as possible, in the "knee" of the curve as Bob so famously preaches...
Suggestions?
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You need to try a variety of hammer spring preload settings and graph the velocity vs. preload, like this.... The knee on this curve is 4-5 turns out....
(http://i378.photobucket.com/albums/oo221/rsterne/QB%20on%20HPA/QB79NinjaDelrin1200_zps999456be.jpg) (http://s378.photobucket.com/user/rsterne/media/QB%20on%20HPA/QB79NinjaDelrin1200_zps999456be.jpg.html)
Once you know what the curve looks like, you will know if you can reach the knee, or it you need to clip the spring.... it will also tell you if you need to change the pressure.... Do that and post the results....
Bob
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I am thinking I might exchange my chronograph for the one that comes with the indoor lighting attachment. I only had a chance to play with it once so far and only for about 20 minutes. Today it is supposed to rain all day so I don't know if I will get the chance today either!
Anyway, i have not yet had the chance to plot a graph. I do know that when I had the RVA all the way out, the heavy pellets were at about 790fps, and they got up to about 895fps when I went maybe 3-4 turns from the point where I felt the spring start to engage. I then turned it way in, not counting the turns because I was in a hurry, to a point where cocking the gun was very difficult, and I got a couple at over 920fps. This would mean that the knee is in there somewhere, right?
My goal is to be able to adjust the lighter pellets down to maybe 750fps, while still being able to achieve an efficient 875-900fps with the >10gr pellets and a few turns of the RVA.
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Not necessarily.... If the velocity is still increasing at 920 fps, you may not have enough hammer strike to reach the knee.... That is unlikely, however, but is the reason you have to test it to know where the knee is.... ie the optimum velocity for the pressure you have....
When you adjust the RVA for lighter pellets at ~ 750 fps, be aware that when you reach the setpoint, the velocity will start to INCREASE below that, just like in an unregulated PCP....
Bob
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Not necessarily.... If the velocity is still increasing at 920 fps, you may not have enough hammer strike to reach the knee.... That is unlikely, however, but is the reason you have to test it to know where the knee is.... ie the optimum velocity for the pressure you have....
It may start increasing above 920, but I don't think so. After getting 895fps, I saw very minimal gains turning things in after that. I saw maybe 900-905 after a few turns in beyond 895. I don't know that I would ever turn the RVA in so far as I did when I saw 920... It was almost impossible to cock. I am thinking optimum velocity for this may be about 890 or so, with the spring I have currently. I guess I will find out tomorrow, unless I can figure out how to get this chronograph working indoors...
When you adjust the RVA for lighter pellets at ~ 750 fps, be aware that when you reach the setpoint, the velocity will start to INCREASE below that, just like in an unregulated PCP....
Are you referring to the increase in velocity I would see once I drop below regulator pressure, due to the vastly increased plenum (the bottle) size, or some other increase that would happen with even lighter spring pressure? If so, I am not sure I follow...
What I am after is two power settings, one for the heavy pellets at ~875 or so (biased toward power and perhaps 50 yd FT) and the other for light pellets biased toward high shot count and maybe 20-30 yds.
The idea would be to record the amount of turns it would take to get various lighter pellets to the velocity I am after...
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The very first post in this thread should explain it....
http://www.gatewaytoairguns.org/GTA/index.php?topic=74919. (http://www.gatewaytoairguns.org/GTA/index.php?topic=74919.)
Graph it out, you don't need to use a computer, graph paper will do.... You will see the plateau, knee, and downslope instantly once you do that....
Bob
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I see. You were referring to the slight increase shown in your downslope tune. This is good to know! I have been considering trying to get away with the higher efficiency of the downslope, and now I will definitely be tuning the heavier pellet right to the knee. The slightness of the increase means I would likely be okay with it when plinking with the lighter pellets. Thanks for the info!
In my case, regulator creep refers to the fact that I have ~1450psi output when I have a full (~3000psi) bottle, and maybe ~1400psi when the bottle has a ~1500psi fill, correct? I am confused, because I would think that the downslope line on your graph would move in the opposite direction, as slightly higher output pressure should equate to slightly higher velocity. What am I missing here?
Anyway, the weather let up a little (well, my brand new Caldwell Chronograph did get a little wet!) and I had a chance to record some velocities. All numbers are three shot averages, and I made sure the bottle always had over 2000psi in it. Of course, this was before I read your regulated tuning post, so I guess they could use some slight adjustment. Extreme spreads were generally no more than 5fps (which I am ecstatic about!), so I just did some redneck math in my head to come up with the number.
I changed to measuring "turns out" instead of "turns in" as I noticed that that the point of initial spring engagement moves around a bit as the spring rotates inside the gun. When I turn the RVA all the way in, it stops at the same point every time, so I will likely be putting a little stamp or scratch in the knob to mark this...
Velocity does not increase at all under 7 turns in. I did not notice any notable differences until I got to 9.5 turns. Here are my results:
Turns out Velocity
7 932
8 929
9 929
9.5 917
10 911
10.5 909
11 900
11.5 886
12 879
12.5 865
13 853
13.5 839
14 820
I did not bother to make a graph, but this would put the knee at about 9.5 turns out, correct? I will have to shoot some groups to see what kind of accuracy I am getting at this velocity, but it does seem a little high, in the transonic region I see so many writing about...
I noticed that as I got past maybe 13 turns, the spreads would widen up quite a bit, maybe as much as 20fps. This has me thinking that I want to always use the gun with a moderate amount of preload to keep extreme spreads low.
All my lighter pellets ranged from 930-975fps with the RVA knob all the way out and completely removed from the gun.
Based on this data, I am thinking the first thing to do would be to try lowering set pressure a tad to bring that knee (and find it again!) down to a velocity I am more comfortable with, say ~900fps. Once that knee is at the velocity I want, I can then look at clipping the spring to a length that will accommodate my heavy pellet knee, and allow for lower velocities with lighter pellets ...Does that sound right?
EDIT: Oh yeah, I have noticed that the hammer seems to be getting jammed when cocking it now, since I had to pull back on it pretty hard when I was cocking it at the heaver preloads. Have you run into this? I am going to try putting some grease (or maybe dry PTFE lube) in the tube to see if this fixes things. Nothing seems damaged when pulling things apart, but it sure is hard to cock now, even with no preload!
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You need to read that thread on tuning again.... When you are tuned on the Downslope, lower pressure results in higher velocity, until you hit the peak of the velocity curve just as if you were shooting an Unregulated PCP.... That is why the velocity may show a slight increase as the tank drops from 3000 psi to the setpoint.... Once you reach the setpoint, then the rise in velocity is sharper and although I only showed about 20 fps in that graph, it can, in fact, be over 100 fps if you are tuned far enough down on the Downslope.... As an example, consider an Unregulated gun tuned for 1000 psi and then filled to 1500.... The velocity would start slow, rise, peak, and then decline.... If you ran that gun on a 3000 psi tank with a 1500 psi regulated output, it would stay relatively close to the velocity it did at 1500 psi until it dropped below that, then it would act exactly like it did without the regulator....
You are definitely on the plateau at 7-9 turns out.... You are on the downslope past 11 turns out.... The knee of the curve is in between 9-11 turns.... That is only a range of 30 fps, about 3%.... so you can tune anywhere in there and get good performance.... The closer to the plateau, the more air you will use.... I would expect that 10-10.5 turns out would produce the best balance between power and efficiency.... If you really need to reduce the velocity 10 fps, then you can reduce the pressure by maybe 50 psi.... I personally would try all the settings between 9.5-11 turns out and see how many shots you can get and pick a setting.... It looks like you are VERY close to what you want, so close it may not be worth resetting the regulator....
You likely bent or galled something at the higher preloads.... Have a look at the hammer cocking pin, and the slot it runs in.... also the bolt handle....
Bob
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Okay, so I have read and reread that post... Let's try this again! It helps me if I look at things at their extremes, here is my take on how I am (shakily) understanding things:
Let's say we have pressure that is so high that the hammer (and spring) is unable to overcome it at all. This is valve lock, right? My use of terms may be shaky here as well, more on that in a minute. Let's say we lower our pressure (or make the hammer heavier, increase spring pressure, install a heavier spring, etc) to the point where the hammer is just barely able to open the valve. We would have an extremely small amount of air released, and the projectile would barely move. The more we keep lowering the pressure (or increasing the force with which we strike the pin), the more air is able to escape, and velocity increases with each shot until we reach a peak. Then velocity falls because we again have less air escaping, this time because the air pressure itself is low enough to cause it not to be able to escape as quickly.
Yeah! I think I get it now. The slight increase we see due to regulator creep is the same as what we see as we are getting away from valve lock in an unregulated setup. If we back the RVA on our regulated guns so far off that the hammer barely strikes the valve pin, we again have valve lock. This seems right. Am I using the term "valve lock" correctly? Also, it is a "pin" that the hammer strikes against, isn't it?
On to incorrect use of terms. I have been saying that I use the gun for "FT" ... I assumed that the word "field target" meant plinking out in the woods, making acorns and pebbles bounce around. This is the kind of shooting that I enjoy ... hiking with a gun in my hands, maybe harvesting an occasional squirrel or splattering an insect or three. I guess this is just "plinking" ... I did not realize that "Field Target" was an actual discipline that people compete in. This is not something I have ever done, although it sure sounds fun! I apologize for any confusion!
I think I am going to remove a shim and see if I can still achieve 900fps with whatever the lowered pressure turns out to be. I figure I might be able to wring out a few more shots this way... I can always go back. I know that the knee will always be based on whatever ~10gr pellet I decide to use, and I will just have to live with the slight rise in velocity when using the lighter pellets.
As far as clipping the spring for the lighter pellets, is there any kind of good methodology to follow? Would it be better to have the clipped side touching the back of the hammer or on the RVA side? How much should I clip off to start? I figure I am safe so long as I start with a length that is shorter than the distance my RVA is backed out at the knee. It turns out I have an extra spring, as when I ordered my parts from Crosman, the guy on the phone said that the RVA did not include a spring, although it did. I am also thinking it would be better to remove all spring pressure when I am done for the day, as I do not want the spring to set, just as the springs in spring piston guns do ... Is this really an issue with regulated PCP's? Is there such a thing as a gas piston hammer spring? Hmmm... :D
As far as the stiff cocking, I am embarrassed to say that I had the barrel mounted off center to the transfer port. This in turn caused some undue pressure on the tube and things were not quite lined up correctly. The gun cocks fine now, and I added some dry PTFE lube for good measure...
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Sounds like you got it!.... "Valve Lock" to me, is when you can't get any air to shoot from the gun, the pressure is too high for the hammer strike.... Some use that term for any time the velocity is less than maximum because of high pressure.... I would call an extreme case of that "partial lock", but a small amount is just normal tuning for an unregulated PCP....
I would put the clipped end inside the hammer.... You can bend the end closed if you wish, but I don't think it really makes a difference.... There is NO need to release the preload on a spring, in fact leaving the gun cocked will not normally hurt a spring, and certainly not one that has been "set" (compressed to coil bind) even once....
Bob
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Hmm... So it seems that if I want to split some hairs, the true sweet spot would be where I can maintain that same 5fps velocity spread for as many shots as possible below regulator set point... Of course, then I would have to live with whatever velocity I come up with there, and there is just something cool about saying "my gun shoots 900 fps...". Of course, I still have yet to determine what velocity will give me the best accuracy at 50 yards on this gun, and with these pellets... I did shoot some quick groups the other day and achieved about 1 inch at 50 yards, and that was right at 900fps. It was getting dark and misty though, there was also a little 5-7mph inconsistent breeze and I was using peep sights. I guess the real measurement would be to make sure i have a few hours on a still day, put a scope on there and shoot some groups that way...
Anyway, why is it not required to release preload? Is it because the spring lighter? Do springer springs compress further than ours do when cocked? What other factors would make them not as affected by fatigue?
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The spring in springers is often pushed very close to the yield point, and are MUCH more highly stressed.... I don't know what you have read about leaving them cocked, but they lose about 5% after several MONTHS of being left cocked.... After a week, it is less than 1% loss.... and some of it comes back when uncocked....
BTW, while the regulator is probably capable of holding 5 fps, not many regulated guns are better than 1% unless you weigh and measure all your pellets.... because THEY can vary 1% or so.... Unless you are shooting over 100 yards, a 1% ES is more than adequate....
Bob
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I see.... I did not know that the loss in spring strength was so nominal. Really all that i have read on the subject are a maybe a few Tom Gaylord articles on "nitro piston" brands, and the lack of spring wear that is their main selling point. I was never really all that interested in the articles either, since I never really considered getting a springer because of a bad experience I had with one I considered buying from a buddy several years ago. I did not know about the "artillery hold" and I couldn't get it group well. I went through maybe 5 different springers at the time and they all went back to the store for the same reason.
At the time I was enamored with the power claims of the air force condor, but ultimately decided on a CZ-452 ultra lux, which has proven to be ridiculously accurate. I was really happy when I moved to the country last year and discovered I could legally shoot as much as I want right off of my deck. I didn't even have to take off my slippers if I didn't want to! In was happy until I ran out of bullets anyway. Then the .22lr bubble had me spending over fifty bucks for 500 rounds... First thing I did was start reading about the condor again, but the shot counts and bell curves just weren't doing it for me. The whole artillery hold thing for springers just seemed unreasonable to me. While i did notice an improvement with my red ryder, accuracy being as bad as it is with that gun, holding a gun that lightly feels unnatural to me.
Because of these things, my interest in shooting was starting to wane once again, until I saw your qb79 ninja article. 100 shots with no curve seemed too good to be true! That got me REALLY interested once again, and I have you to thank for that.
As for my 5 fps claim, I thought it was a little tight, but I was not exaggerating. These were just a series of three shot groups as i backed off the spring a half turn each time though. Pellets were just picked from the tin, I don't even own a scale! Spreads only opened up when preload was at ts lightest, though I don't know why.
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5 fps is great if you can get it.... just not necessary unless you are shooting at 200 yards.... 1% at 100 is just fine.... Chrony your .22LR ammo some day and see what the ES is over a box.... you will be shocked.... and yet they still shoot MOA at 100 yards....
Bob
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Okay waitaminnit. I can't say I have ever really considered 200yards with an airgun... Certainly not with my .177 cal...
What kinds of distances have you tried?
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I have a confirmed kill on a Ground Squirrel at 106 yards, mind you on the second shot (.22 cal 18 gr.@ 960 fps).... Carl just posted about hitting a 39" square steel plate repeatedly at 1065 yards.... and pop cans at 700.... Check out the Big Bore gate.... Also, the last gate in the Target Shooting section is the Long Range Club.... N.U.A.H.... which means "Nothing Under a Hundred" (yards).... Pellets at 100 yards are challenging but getting more commonplace.... Bullets at double that is where you really need to get down to about a 1% ES....
Bob
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Okay so what about actual group sizes at these crazy ranges? I will definitely test myself, but it am wondering what kind of group sizes I might see with my .177 at various ranges.
And check this out:
900fps with a 1250psi set point! I was at about 905fps with the adjuster all the way in and I was at about 895 with 10.5 turns out. 887 with 11 turns! Cool! I also removed the ball and seal from the bonnet and filled with everything hooked to the gun. Perhaps whatever slight increase this provided to flow and plenum size helped keep the velocity up as well. I am super happy about this! Time to start cutting my spring...
EDIT: Hmmm. Look at the differences between these springs:
(http://i1066.photobucket.com/albums/u404/appye/Mobile%20Uploads/image.jpeg) (http://s1066.photobucket.com/user/appye/media/Mobile%20Uploads/image.jpeg.html)
Neither of them have been clipped. The short one is what has been in my gun for a few weeks. The springs were identical when I got them.
...is this normal? I am gonna be clipping the short one in a few minutes...
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EDIT: Hmmm. Look at the differences between these springs:
(http://i1066.photobucket.com/albums/u404/appye/Mobile%20Uploads/image.jpeg) (http://s1066.photobucket.com/user/appye/media/Mobile%20Uploads/image.jpeg.html)
Neither of them have been clipped. The short one is what has been in my gun for a few weeks. The springs were identical when I got them.
...is this normal? I am gonna be clipping the short one in a few minutes...
Well it sure looks to me like the lower portion of the spring on the left (longer one) has been "stretched". The upper coils match with the right spring, but the coils at the bottom appear to have a larger gap.
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The shorter spring has been "set".... My guess is that if you take the long one, put it on a rod so that it can't kink, and compress it fully (to coil bind), just once, it will be the same length or shorter than the short one.... That is why I always set my hammer springs before I use them for the first time.... If you do that, they will never change again.... and neither will your preload settings....
Bob
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... spring on the left (longer one) has been "stretched".
This might be wide angle phone camera tricks... Not sure. The one on the left looks exactly as it did when I first got it, which is exactly what the other one looked like.
The shorter spring has been "set".... My guess is that if you take the long one, put it on a rod so that it can't kink, and compress it fully (to coil bind), just once, it will be the same length or shorter than the short one.... That is why I always set my hammer springs before I use them for the first time.... If you do that, they will never change again.... and neither will your preload settings....
Bob
Hmm. I never thought of that. And I already cut the short one! I will make sure to set them with my RVA knob and my "degasser tool," a 4" 10-32 screw I got at the hardware store... I hope the short one will still get me my 900fps ... If not it is good that I have a spare...
Speaking of which, I am really glad you suggested that RVA from the challenger... I can't so easily remove the spring I guess, but I like how closely to complete spring bind it gets to before stopping, and I dig that the knob is also threaded for the degasser tool. However, it seems to have a hole for a set screw, but that hole is not threaded. Is it supposed to be like this? If so, what exactly is that hole for?
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It is for a plastic plug to provide friction so that it doesn't self-adjust....
Bob
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I don't mean to hijack your thread,, I'll apologize for that in advance.
But I have a question regarding pinning the valve. I'm planning some mods on my own 2400kt. I plan to use a HiPac system with extensions. My question; is the single valve screw sufficient If using a HiPac system or do I need to add the two extra screws as well?
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If you upgrade the lower valve screw to 8-32, as per the HiPac website.... and providing you are using the HiPac as designed.... you should be fine.... Obviously additional screws are OK, if you want to do that....
Bob
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If you upgrade the lower valve screw to 8-32, as per the HiPac website.... and providing you are using the HiPac as designed.... you should be fine.... Obviously additional screws are OK, if you want to do that....
Bob
I do indeed intend to install the HiPac system exactly as it was design to be. I saw what happens when big dumb rednecks go monkeying with it.
I'm not sure it's worth mentioning but I have a "high performance" valve from Alliance airworks installed that has an angled port and gives greater volume of airflow.
My intention has been to use the HiPac conversion for both HPA and bulk fill CO2 use. It will be unregulated. CO2 charged primarily, and HPA for colder weather use. Anything I should be aware of/prepared for?
Again I apollogize for hijacking the thred...guess I should just start my own when I get closer to being ready to start buying parts.
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I think HiPac says the factory screw is sufficient below 2000 psi. Going with a hi flow valve won't affect anchoring requirements.
What I did with my two HiPac'd Crosmans is keep the original screw and add a pair of 8-32 screws, one on each side.
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I think HiPac says the factory screw is sufficient below 2000 psi. Going with a hi flow valve won't affect anchoring requirements.
What I did with my two HiPac'd Crosmans is keep the original screw and add a pair of 8-32 screws, one on each side.
Did you by any chance do a write up on the machining for that?
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I think HiPac says the factory screw is sufficient below 2000 psi. Going with a hi flow valve won't affect anchoring requirements.
What I did with my two HiPac'd Crosmans is keep the original screw and add a pair of 8-32 screws, one on each side.
Did you by any chance do a write up on the machining for that?
here is a good read right at the top of the PCP gate
http://www.gatewaytoairguns.org/GTA/index.php?topic=97198.0 (http://www.gatewaytoairguns.org/GTA/index.php?topic=97198.0)
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No. Actually all I did was drill through the tube and into the valve (with a depth stop), thread both the tube and valve with a bottoming tap, and put an 8-32 set screw in it. Then flip the tube over and do the other side.
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Hi All,
I figured I would post a couple of pics so you could see what it looks like at the moment:
(http://i1066.photobucket.com/albums/u404/appye/IMG_0215.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0215.jpg.html)
(http://i1066.photobucket.com/albums/u404/appye/IMG_0214.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0214.jpg.html)
I am still not quite done with mounting the bottle, but it sits pretty solid as it is now. I found a scrap of UHMW polyeurethane, drilled a couple of matching holes (to the tube and the bottle) and cut it down to where they look like a couple of giant barrel bands. They are obviously still rough around the edges, and I hope to clean that up this weekend. Also, I am likely going to be removing one of them when I jbweld a piece of metal or plastic to the back of the bottle that will insert into the remainder of the factory forestock. This should make it feel really solid if I can get it to fit snugly into a recess that is in the forestock. What I ultimately plan on doing is using more of the polyurethane to make my own forestock, a little smaller and with finger grips. The gun balances perfectly in my hand at that spot, leaning forward just the right amount so it is pointed at the ground when I carry it at my side. Ergonomics are absolutely stellar. I thought the 17" length of pull was gonna be too much, but it really feels natural to me. This is the first pistol grip rifle I have owned.
So far, I have polished the trigger, which made a big difference. I also touched up the crown with the brass screw trick, and only lightly polished the barrel with fitz and paper towels around a spiral jag. It is definitely shinier than before... My cheap multi piece rod broke while I was doing it. I still haven't polished the leade/bore transition. When i get a nicer rod, I really want to try my hand at lapping the barrel with molten lead, as I have seen people do on YouTube. I have my 1377 and an old 22lr that (according to my brother, who gave it to me) "shoots a little squirrely" to practice on.
Anyway, this gun has exceeded my expectations. In its current state, I am shooting dime size groups (well, consistently under an inch anyway) at 50 yards (scoped and bag rested while I am testing pellets) with the JSB heavies at 900fps. My goal is to be able to match the 50 yard accuracy of my CZ-452 ultralux, which can do quarter inch CTC groups at that distance. So far, I have not been able to get any of the lighter pellets to group quite so well, but most of them still group at around 1-1.5" at that distance, and I have not had a chance to test everything I have. Lighter pellets will primarily be used for shorter distances anyway. Crosman destroyers (~1¢ at Walmart) were suprisingly accurate at about 11 turns out, which I would guesstimate to be about 750fps at the muzzle. I haven't clocked those yet. CPHP's group the worst so far, with perhaps a 4" average no matter where I adjust the RVA. I am anxious to try out some of the 9.8gr winchester domes at PA ... They are so cheap! Anyone have experience with these?
I love being able to adjust to different velocities and really see where I can get different pellets to shine. Today has been cold and rainy, and I called in sick to work. I have been shooting indoors with different wadcutters (offhand) and am able to make single hole at perhaps 7 yards or so... Even the cheap daisies are decent enough at this range. Daisy pointed or hollow point still group at nearly an inch even at this distance... I have the RVA way out to 13.5 turns and I am maybe shooting 500fps or so. My dad got me an indoor light kit for my chronograph that should arrive this weekend. I can't wait for it! This weekend I will be able to plot more velocities and decide on some favorites at different power levels.
So on to the little plastic (neoprene perhaps, like on lock nuts?) thingie that is supposed to go into the RVA, providing friction to stop it from self adjusting... Was this supposed to come with the RVA? If not, is there a crosman part number, or a decent DIY solution anyone would like to share with me? It isn't such a big deal when the knob is turned in a bit and there is already a load on the spring before cocking, but when I am shooting indoors, the knob is turned way out and there is no preload on the spring until the gun is cocked, allowing the knob to turn a little too freely. I did try using teflon tape with some success, but it felt a little too elastic somehow ...
EDIT: Bob. You are starting to become an enabler here! This airgun thing is becoming quite the obsession for me! Now, am reading a post you made about a boattail pellet for PCP's and it has me interested in in casting now! Wonderful. I am not made of money you know... Five months ago, I was just considering a cheaper alternative to 22lr, and was only passingly interested in airguns. Today, I am hopelessly addicted.
Moral of the story: If you have a significant other who thinks you spend a little (a lot) too much time with your airgun(s), blame Bob. Okay, so where's that needle ...
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Okay cool. I called crosman and they are sending me a new "acetal pin" (CH2009-023) that will work to keep the adjustment knob a little stiffer... I am assuming "acetal" is similar to the material seen on locknuts that keep them from spinning...
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Acetal is the generic name for Delrin (a trade name)....
Bob
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Okay, this is weird. I finally got my bottle mounted the way I wanted and decided to pull the gun apart and put it all back together with everything just so, with some lock tight in a few key locations and generally a little extra TLC. I did this because of all the disassembly/reassembly that has been done over the last few weeks while tuning, clipping springs, etc. I thought I had everything really nicely set up!
What I am running into now is some sort of extreme hammer bounce... Really extreme. It even happens on the low power settings, but I didn't really notice it until I pulled out my heavy pellets and turned the adjuster in. I get obvious "Brrrraaappp" sounds when I fire now. With the adjuster turned all the way in, I got literally a full second, maybe even two seconds of the long burp sound. Literally! It sounded like a machine gun. Any idea what is going on?
When I last took apart the gun, I noticed that the spring was sort of stuck in the adjuster (a challenger RVA), even with the knob removed. I didn't really think much of it though. I just left the spring in there and reassembled the gun. Perhaps I should have taken it out! What in the world is happening???
I am thinking of drilling out a bolt and trying the spring guide mod Bob came up with a few weeks ago where the hammer actually coasts into the valve pin, eliminating hammer bounce. I am not sure how much advantage I would see with this mod on my gun though. I really would like to get my gun working properly on its own beforehand...
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Sounds like low pressure. Do you have a test gauge to see what your regulated pressure is?
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If your spring is sticking in the adjuster, my guess is that you used too long a screw (top or bottom) and damaged the spring and it's hanging up.... Whether that is causing the hammer bounce or not I don't know.... The worst hammer bounce I ever experienced was with a very light valve spring in a .35 cal Disco conversion.... When the air pressure got low enough, it bounced until it emptied the reservoir.... Too much preload at too low a pressure is the basic cause of hammer bounce....
Bob
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I am gonna check out the spring first... I tested my regulator at 1200-1250psi a couple weeks back, but I may as well double check that. I did replace the bottom screw on the RVA, but I made sure I used the same length...
This was definitely not happening before this last, partial teardown...
Another thing I did differently upon assembly, now that I think of it, was to clamp the receiver to the tube. The breech was a little loose on the tube, which prompted this whole thing in the first place. The small, forward breech screw was never removed until the clamps were in place. I then removed the screw, which was very loose, put some locktight on it and snugged it back down... After installing the rear screw, I removed the clamps. I did at least attempt to only lightly clamp things together, but now I am hoping I did not damage something...
I will find out tonight...
EDIT: Hmm. I just thought of another difference. When I last took the thing apart, I degassed it with a 4 inch screw I picked up from the hardware store. The screw threads right into the knob from the Challenger RVA. I have done this several times before with no ill effect. This time, I noticed I a small, low pitched squeal coming from the gun after I backed the screw off. I then turned it back in (perhaps further than before, I don't really remember) to release whatever tiny amount of pressure was still in the gun. If I did turn it in too far, perhaps I weakened the spring inside of the valve ... I know I didn't go all that much further in, but I dunno.
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Doh! I haven't put it back together yet, but uh ... I'm gonna say I think I found the cause of my sudden hammer bounce! My daughter started calling it "Dad's Fart Gun" ...
(http://i1066.photobucket.com/albums/u404/appye/IMG_0239.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0239.jpg.html)
(http://i1066.photobucket.com/albums/u404/appye/IMG_0240.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0240.jpg.html)
I guess I wasn't paying attention when I last put the thing together. Anyway ... relief!
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Is that the valve spring?.... *LOL*.... I didn't realize they used T-----s....
Bob
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Yep ... ::) I had some tissue paper stuffed into the tube when I had the gun opened up, just to keep anything from falling in. Then forgot about it I guess... I would definitely advise AGAINST the use of tissue paper valve guides...
I have not read it in a lot of detail as of yet, but I saw your thread on your "SSG" valve guide idea. Very interesting. Have you seen improvement on regulated bottle guns such as mine, or your QB79 Ninja/$200 PCP (http://www.gatewaytoairguns.org/GTA/index.php?topic=49943.0)? I plan on reading that thread tonight...
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Yep, good improvement on the Ninja, it's all in the thread.... Works on regulated and unregulated PCPs....
Bob
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I saw that. I am definitely gonna be doing this in the coming weeks. Maybe this weekend!
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Man ... I am so happy I chose a 24" barrel! I lowered the pressure AGAIN! I am down to 1050-1100psi and I am STILL getting high 890's, even the occasional shot a hair over 900fps with the 10.34gr jsb heavies! This is with the RVA turned all the way in. I am not sure where the knee is now, as I have not clocked too many pellets at this pressure... I guess I will have to find it again. The main reason I did this was to see if I could eek out a few more shots per fill before building my SSG.
Thanks again everyone for all your help. Bob (rsterne) is first and foremost on that list of course... Rob (BigTinBoat), I got a lot of good information from you as well. Todd (HappyHunter) provided the tipping point for me going with a crosman instead of a QB... I just love the ultralight form factor. Last, but not least would be Jason (NervousTrigger) who provided me some pretty good information on massaging my barrel, which I followed pretty closely. I couldn't have done it without you guys. Thanks again!
Now, off to the hardware store. SSG, here I come!
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I don't want to derail the SSG thread with questions about my specific setup, so I am posting my question here... First, I was very successful in making and installing an SSG with my drill press, bench grinder, and some dremeling. I used my smartphone to make a super slow motion video (240 frames per second) of my gun shooting before installation, and it recorded an average of four 4 bounces per shot. It recorded NO bounce at all with the SSG installed. I am able to achieve the same 900fps with 10.34gr JSB's as before, and hammer bounce has been stopped cold. Awesome!
Anyway, I am now noticing that my extreme spreads are quite large compared to before. Most pellets are spread out as much as 35fps, compared to the ~5-8fps (depending on the pellet) I was experiencing before I lowered from 1200-1250psi. A couple of days before I made the SSG, I lowered my set pressure to about 1050-1100psi. Theoretically this would mean more shots per fill, right? This lowering of the pressure is what introduced the hammer bounce in the first place. At least, it is what made it sound more obvious. I was excited that I was still hitting ~900fps with the lower pressure, and I did not bother to check for ES. I went straight into making the SSG. At first I was thinking it was the SSG, but I now see that I have the same wide ES with or without it installed, so I figure the problem must be related to the low set pressure.
My thinking is that this Disco valve is not really meant to run at such a low pressure, but I know zilch about how to balance hammer and valve springs for efficiency. Other than raising the pressure back up, is there anything else I can do to tighten up the ES again? I was thinking maybe I need to lighten the valve spring, but I don't know for sure so I figured I would check here before taking things apart again. Currently, the hammer is what came with my 2400kt. The valve, valve spring and hammer spring are all unmodified Disco parts. The only other spring I have to play with at the moment would be the spring that came with the original 2400kt valve ... I don't know if it is any different. I can always go to the hardware store...
This gun is a CCS 2400KT in .177 with a 24" barrel ...
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Sorry haven't run a Disco/22XX setup at those low pressures, with the exception of an <500 fps bottle gun running on about 500 psi with a 2240 spring with only 1/16" preload.... so I can't offer any advice on spring choice.... However, trying to maintain a given (relatively high) velocity (eg 900 fps) while lowering the setpoint pressure (eg from 1250 down to 1050) is a perfect recipe for wasting air from hammer bounce.... You are moving from the knee of the curve up onto the plateau, and that is exactly where hammer bounce occurs.... It is for this reason you often get more shots with a higher setpoint pressure on a regulated gun.... Read over my thread on tuning a Regulated PCP again....
Bob
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So you are saying I am wasting air, even with bounce completely eliminated by the SSG? I will admit to never actually testing shots per fill... At 890fps with the gun as it is currently, it is definitely not on the plateau... If anything I cannot quite reach a plateau, as 1 turn out is already about 870fps. The idea was to stick with that velocity.
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Hmm, this is an interesting topic. If appye's tune is now up on the plateau, it makes sense that air use and hammer bounce may be worse. But I don't see the correlation with the higher ES. Up on the plateau, having a bit more or less hammer strike will do little to the velocity, meaning that although it is wasteful of air, it will be more tolerant of little things like friction or sear drag that would tend to drive up the extreme spread.
I wonder what is causing it.
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If you are not on the plateau, you will not be waisting air.... What I meant was that when you reduced your setpoint from 1250 to 1050 (pre SSG), you may have moved up onto the plateau, the fact that you were experiencing hammer bounce would confirm that suspicion.... The plateau is were the dwell is so great that little if any velocity is being added to the pellet, and eventually it may be exiting the barrel while the valve is still open.... That could still happen with the SSG in place, what can't happen (assuming it's tuned correctly, with enough preload and a gap) is for the hammer to bounce.... However, with the right (wrong) combination of spring and preload you could still get enough dwell to be dumping air after Elvis has left the building.... When you lower the setpoint pressure, you lower the velocity where the plateau occurs.... Are you absolutely sure you are not on the plateau at your lower setpoint?.... Did you try various preloads before you installed the SSG to confirm that?.... What velocity is the new (lower) plateau at?....
Jason, I agree that the ES should not increase on the plateau, it should decrease.... Likely something else causing the increased ES.... drag somewhere....
Bob
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I don't want to derail the SSG thread with questions about my specific setup, so I am posting my question here... First, I was very successful in making and installing an SSG with my drill press, bench grinder, and some dremeling. I used my smartphone to make a super slow motion video (240 frames per second) of my gun shooting before installation, and it recorded an average of four 4 bounces per shot. It recorded NO bounce at all with the SSG installed. I am able to achieve the same 900fps with 10.34gr JSB's as before, and hammer bounce has been stopped cold. Awesome!
How were you able to "film" this? Do you have the video posted somewhere we can see it?
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I was thinking drag somewhere too ... When I finally chose my spring/rod length combination for the SSG, I was using this really bunged up rod that I had marred up quite a bit... The gun sure seemed to be shooting with a tight ES though. I did not really look too hard for it, maybe 5 shots, take it apart, try another spring, 5 shots ... So the wide ES may or may not be due to my having worked on the gun. Maybe even some metal shavings have made their way in between the tube and the hammer. Anyway, I noticed the widened ES when I remade the SSG with a brand new, not bunged up section of rod. It is nice and smooth... I will pull it apart and make sure all is clean. I may even take the time to polish up the rod and bolt with some fine sandpaper... I am thinking drag might be with the tube and hammer though... I will find out tonight.
Part of what made me so excited about the SSG was it seemed it would give me the ability to go with an even lower set pressure, seeing as how hammer bounce was mitigated.
As far as how I filmed it, I used my phone. This particular phone is the iphone6 that my work issued to me. It has "slo mo" function to the camera that allows me to film at 240 fps vs the standard 24.x fps of standard video. The result is a video was initially filmed at 240 fps but plays back at 24fps... you get a video that is in super slow motion. It is a really nice way to detect FOR SURE if you are getting hammer bounce. Most newer smartphones (from maybe the last 2 years) have this feature... I know because I have about a solid hour's worth of my daughter shaking her hair around in super slow motion! If it is not built in, then look for "high speed camera" in your app/play stores... It was nice, because it slowed down the entire shot (including bounce) to about a full second, allowing me to actually count the bounces.
...Aaaand I just figured out how I can share it. I published a couple on youtube. It is really cool, because the youtube player allows you to slow down the resulting video by half again and still hear the audio. Here is a link to the PRE-SSG video:
https://www.youtube.com/watch?v=Da5F0_-Gv7U (https://www.youtube.com/watch?v=Da5F0_-Gv7U)
... And here is a link to a video I made at night with the ssg installed...
https://www.youtube.com/watch?v=upB_D6rsWvc (https://www.youtube.com/watch?v=upB_D6rsWvc)
I think I could have made it without so much background noise if I didn't do it from my enclosed deck. I had a wall to my left and a ceiling above me. It can probably be made to sound cleaner if I had done it out in the open...
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So you "audio" recorded it. I thought you could see the hammer bouncing. While maybe that is "hammer bounce", I don't think it is hitting and opening that valve 5 times.
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Well, I could try filming the cocking pin thingie as well, but it sure sounds like it was opening the valve several times... I could hear the "farty" sound every time the gun would fire. What else would it be?
Also, here is another hammer bounce that was recorded at full power. The daytime shot from the previous post was at a much lower velocity and with a lighter pellet. I don't remember what exactly, likely a 8.44gr jsb exact fired at ~800fps, versus the video below is a 10.34 fired at ~900fps...
https://www.youtube.com/watch?v=oMgdU6RCmx0 (https://www.youtube.com/watch?v=oMgdU6RCmx0)
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What else would it be?
Not sure, but wondering where you are holding the mic? and wondering why I don't hear any report?
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Hmm.. I will post a normal speed version of the file as well, so you can hear the difference. It IS the report that you are hearing, just slowed down to where you can hear the individual bounces. I was not holding any microphone, just filming the shot with my phone. Maybe the phone was a foot or two above the gun when it fired. Tomorrow is my day off, so I will film some daytime shots, hopefully complete with a visual of the actual hammer bounce if I can get the phone to pick it up...
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Maybe it is "bouncing" 4 times.
https://www.youtube.com/watch?v=gnR7NwR--aE (https://www.youtube.com/watch?v=gnR7NwR--aE)
Doesn't look like it is opening other then on the first one here.
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I see at least a second opening of the valve.... small but definite (maybe 0.010-0.015").... possibly a third, or it could just be the seat material decompressing....
Bob
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Looks that way to me, too.
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Well, I have been sick for a while, so gun tuning keeps getting put off. I also have not had the chance to film the hammer bounce... Shivering in my bed seemed like a better idea at the time...
I am not so sure I am on board with the idea that it was not releasing air on each one of those pulses. The gun for sure had that farty sound when it was fired. Each pulse nearly as loud as the previous, and while this gun isn't really all that loud, the sound of air releasing from the barrel is considerably louder than just the hammer bouncing on the valve pin when the gun is dry fired with an empty tube. That is the level of sound I would be hearing if the pulse did not open the valve, right? For example, in this video (https://www.youtube.com/watch?v=Da5F0_-Gv7U), I hear FOUR separate releases of air, and a fifth pulse that might just be the hammer landing on the pin and not opening the valve...
Anyway, I put set pressure back to 1200psi (well, I put the shim back in anyway, I did not actually re-test pressure with that particular shim combo, but it is what I had before...) and also put the lighter valve spring in from the original c02 valve... No difference in spread.
It occurs to me that I did one other thing a couple of weeks ago that might be the culprit... I did the barrel work that Jason (NervousTrigger) recommended to me, and perhaps I went a little too crazy with the lead/bore transition smoothing part... I figured I would save some time by using a drill motor to run the sandpaper in the leade by wrapping some sandpaper around a q-tip and spinning it in there. I might have gone too far into the bore itself and widened it somewhat. If this is the case, it could be the cause of my wide spreads, right?
Anyway, I took the shim out again. I still have the lighter (and slightly longer) valve spring in there... As I understand things, this might cause an undesired longer dwell, wasting some air, right? Obviously I am still learning...
....Aaaand I am finding that my benjamin pump is now not able to put more than about 1700psi into the gun. The pump definitely does not feel right... I am likely going to be tearing the pump down and looking for broken parts or something... I am not sure what would cause it to "cap out" like that though, shouldn't it just leak or something? Looks like I am gonna be learning about pump teardowns and whatnot in the near future. I bought the pump brand new just two months ago and it has been in the house the whole time. I have done nothing to it other than put a crappy harbor freight desiccant filter on it... I definitely need to buy some bulk beads and run the air through a soda bottle or something.
EDIT: Another thing to report is that I can hear some air escaping on each pump, even at less than 1000 psi. The more pressure I get into the gun, the more I hear the little squeak I am used to hearing at the very bottom of the stroke, where the air actually gets into the gun being replaced by the telltale whoosh of escaping air. I also noticed I am getting a diminished return for every stroke, where I only gained about 100psi with 25 strokes, where that would normally take about 10 strokes or so... Please tell me I can do this without specialty tools...
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Okay, so I replaced a couple of orings (one extruded into a valve at the top, and the "bumper stop" was torn to bits) and the pump is in working order... I kinda wish I had researched pumps a bit more originally. Anyway, I think I will eventually be replacing all the orings with better ones if such a thing exists. Anyone have any thoughts on material? Rather than getting a kit, i was thinking I would buy them individually in say, ten packs. All the data on oring materials kinda boggles my mind, and I am torn between the ones that have high heat resistance and those with high abrasion resistance since we are dealing with moving parts. I would like to go with 90 durometer where it is good to do so to prolong life as much as possible... Of course, does 90 durometer really mean "durability" or just "hardness?"
Anyway, I think I know what may be the cause of the high ES... When I was initially messing with the first iteration of the SSG, I likely had the end that pushes the hammer milled down off center a bit... Or something. Anyway, there are now twin gouges at the top of the tube where the hammer hits the valve pin. The gouges match the front part of the hammer where it has that bit removed that sort of looks like a bite has been taken out of it. The piece' that is machined away that makes it not completely round? Well, the corners of this bite are what have scarred the inside of the tube.
So the gun is in pieces on my table again. :) I dont know how I missed this before, but it makes more sense because I am 90 percent sure I still had nice tight spreads a good week after doing the barrel work that I was blaming this on a few days ago. Pellets still generally feel tight as I push the bolt (with extended probe) closed too, so I am thinking the barrel is fine.
Anyway, I would like to save the tube if i can. Initially I was thinking of running a hone, but that would introduce its own friction as the tube would no longer be "slick" like it is now... So likely not a good idea, right? It is too far to get in there with sandpaper or my Dremel, though I haven't actually tried that... I was also thinking of cutting slots out that match the gouges, basically removing the section where the gouges are, so the hammer doesn't rub there. I have filed down those same sharp edges of the hammer as well. How far down can I remove those edges? Maybe I could cut some slots in the hammer to avoid the gouges?
Also, since the gun is apart again, and the lighter valve spring didn't seem to change behaviour in any way that I could see, i should put the heavier one back in, potentially reducing dwell time and saving air, correct?
I am grateful for any input you have...
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Valve spring and hammer spring are for the most part interchangeable.... less or one works the same as more of the other.... Having said that, the worst hammer bounce I ever got was on a gun where I tried a light valve spring.... In theory, on an unregulated PCP, a heavy valve spring may extend the shot string to a lower pressure....
Bob
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Okay, so I might want to revisit some of my lighter hammer springs then... The gun is not at all difficult to cock, but if it can be made easier... Why not? Good to know! So my theory about extra dwell time wasting air doesn't really hold water?
Any opinions on my gouges?
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Well, extra dwell time does waste air.... but balancing the hammer spring to your lighter valve spring should fix that....
You shouldn't have to worry about gouges, only bumps.... If you fixed the corners of the hammer, and the cause of the problem, you should be good to go....
Bob
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Appye, regarding your O-ring questions, really the only one in a typical high pressure pump that is worth splurging on is the one on the inner piston. With the Benjamin pump in particular, this O-ring tends to fail more readily due to extrusion than anything else. That is assuming you pump reasonably...do the 'ol jackhammer and heat may kill it. Case in point, a 90 durometer polyurethane has worked well for me despite the fact it has the lowest temperature rating of any common O-ring material. It would seem polyurethane's superior tear resistance wins out. It's great in the area of abrasion as well. Again, this is specifically about the Benji pump. In fact, my particular pump ate an exotic Aflas O-ring in short order as well as a Viton.
Meanwhile everywhere else on the pump has been trouble free with common Buna-N, even on the outer tube which had been neglected by a prior owner and was pitted. I smoothed it as best I could and it has held up fine.
But to address your other question about durometer, yes in general a higher durometer will wear longer in a sliding application. It's also less apt to extrude and tear if the gap is large-ish. Just be on the lookout for O-rings that need to slide. I was unaware and installed a 90 durometer -210 on the Benji pump and it would not work right because it clung too tight and would not slide in the wide groove at the top of the 2nd tube.
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Jason, thanks for the info, just what I was looking for! The small inner piston ring was fine on my pump. I put everything back together with that one and all was well. The one that DID fail on me was between the second and third cylinder. This guy here:
(http://i1066.photobucket.com/albums/u404/appye/IMG_0266%201.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0266%201.jpg.html)
It is interesting that the 90duro polyurethane is holding out better. To me this indicates that failures are not due to heat, but loose tolerances and extrusion of soft rings.
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Wow, amazing that web of material held together as long as it did! Definitely a good candidate for a high durometer replacement.
Regarding the extrusion versus heat failure, I want to stress that was just my experience. You clearly can distinguish the differences so you are in a good position to deal with whatever curveball your particular pump throws your way.
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Yeah, i wamted to replace it with a high durometer ring, but the local hardware store (I am about fifteen minutes from a small mountain town and the nearest city, Fresno, is an hour away) only had orings in the plumbing section, so it is most likely another 55d buna-n once again. I am sureni will be replacing it again... What can I say? I am impatient and wanna shoot my gun NOW! I am also guilty of jackhammering as you put it. Lots of fills from empty during (at least in theory!) the early stages of owning my first PCP, degassing, pulling it apart, etc...
After I got it back together, I tried the idea of "boosting" the pump with my shop compressor on the inlet. I have now filled a couple times this in this fashion, and its nice to be able to pump the gun up in so few strokes. I can imagine this being even harder on the rings... There was already a leak at the base of the of the pump from the moment I hooked the compressor to it, as that ring is compression set pretty badly. I am really gonna have to fashion some bigger dessicant filters, especially if I am gonna continue to do the shop compressor thing, as my little harbor freight filter is most likely still letting some moisture through. Speaking of which, it is about time to get those beads into the oven...
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Hi All,
I guess a clean barrel really DOES matter ... lol. Anyway, after fiddling with everything else, I found I got nice tight ES's when I mounted the 10" barrel from my 1377. I figured that before I wrote it off, I would really try and do a thorough cleaning of the 24" barrel. I grabbed my bore snake that I use on my .22lr barrels, cut the weight off, loaded it with brake cleaner and ran it through about ten times, soaking it through a few times in between. It was VERY hard to pull through! After I was done bore snaking, I noticed that the crown looked like it had some sort of "mushrooming" nicks on the end, like the extra material had been pushed out from inside of the barrel. I don't know if this was because I used a .22lr bore snake on a soft .177 airgun barrel, or due to the fact that the barrel was filthy, but I went ahead and recrowned once again using the brass screw method.
After putting everything together once again, I found that my tight ES's were once again back! Perhaps not to their former >10fps consistency, but I was able to consistently achieve about 10-20fps ES across 10 shots, depending on the pellet. This is at least acceptable to me. Accuracy does not seem to have been adversely affected by running the larger bore snake ... I am still able to pretty much stack pellets at ~20yds, and am able to stay sub 1" at 50 yards. This is good enough for me, as those groups are achieved bag rested and with a scope, but the gun will spend most of its time with a peep sight, hiking along my local hills with me, bouncing pebbles around at 30 yards or so. I have yet to actually kill anything with this gun, so I am getting a little bloodthirsty. Squirrels or rabbits will be this thing's main prey I think. I am confident I can easily drop something like that out to 70 yards or so if I am at full power with the heavies...
I have made a promise to myself to NOT disassemble this gun again until at least the beginning of March!
Efficiency per shot on PCPs tends to go up with pressure, for a given FPE.... In a regulated PCP, however, the "headroom", or the difference between your fill pressure and setpoint pressure goes down, reducing the overall amount of air you have available.... Finding the best balance between the two will give you the most shots at a given FPE.... As you reduce the pressure (like aPpYe is doing), you will eventually get to the point that you cannot get the FPE you want, or you will be operating up on the plateau of the curve where the efficiency is terrible.... and even though you have more headroom (air) available, your shot count will drop.... This has nothing to do with SSGs, of course....
Bob, I once again want to apologize for almost derailing your SSG thread. I wasn't paying attention to what I was doing. Anyway, I am not really sure how all this works with the SSG now in the mix. I was thinking that so long as I am at or below the knee, then the lower I can take the pressure the more shots I would get per fill. More headroom as you say... Currently, I am running at ~850fps with the 10.34gr heavies. With the SSG installed, and the RVA turned all the way in, this is the maximum velocity the gun will achieve. With the SSG removed, maximum velocity is around 885-890fps or so. I am not sure why this discrepancy exists... Interestingly, the SSG installed, I am at ~850fps, from 0-2 turns out on the RVA, and at 2.5 turns, the velocity is around 820 or so.
Anyway, wouldn't this still be considered an "efficient" setup?
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It sounds like from 0-2 turns out with the SSG (at 850) you are on the plateau with that setup, and you have no gap.... You are only getting a decrease in velocity at 2.5 turns out, which is when the gap is starting.... If you want more velocity, you will either need more pressure, or a longer, softer spring on the SSG with more preload to get the hammer energy back up to what it was without the SSG....
I can't comment on the efficiency without hard numbers as to total FPE and total air used....
Bob
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Okay, hard numbers this time. I ran out of jsb heavies, so I had to wait for new ones to arrive. Being without decent pellets is PROBABLY not as bad as being without heroin, but I tell you it isn't fun!
All better now.
First, I shot these groups. The "Description" field shows the amount of turns out:
Set: 1
Created: 02/13/16 08:36 AM
Description: 0 Turns
Notes 1:
Notes 2:
Distance to Chrono(FT): 1.50
Ballistic Coefficient: 0.031
Bullet Weight(gr): 10.34
Temp: 44 °F
BP: 30.25 inHg
# FPS FT-LBS PF
5 859 16.94 8.88
4 875 17.58 9.05
3 868 17.30 8.98
2 881 17.82 9.11
1 865 17.18 8.94
Average: 869.6 FPS
SD: 8.6 FPS
Min: 859 FPS
Max: 881 FPS
Spread: 22 FPS
Shot/sec: 0.1
True MV: 873 FPS
Group Size (in): 0.00
--------------------------------------------
Set: 2
Created: 02/13/16 08:39 AM
Description: 1 Turn
Notes 1:
Notes 2:
Distance to Chrono(FT): 1.50
Ballistic Coefficient: 0.031
Bullet Weight(gr): 10.34
Temp: 44 °F
BP: 30.25 inHg
# FPS FT-LBS PF
5 854 16.75 8.83
4 875 17.58 9.05
3 874 17.54 9.04
2 865 17.18 8.94
1 860 16.98 8.89
Average: 865.6 FPS
SD: 9.0 FPS
Min: 854 FPS
Max: 875 FPS
Spread: 21 FPS
Shot/sec: 0.1
True MV: 869 FPS
Group Size (in): 0.00
--------------------------------------------
Set: 3
Created: 02/13/16 08:41 AM
Description: 2 Turn
Notes 1:
Notes 2:
Distance to Chrono(FT): 1.50
Ballistic Coefficient: 0.031
Bullet Weight(gr): 10.34
Temp: 44 °F
BP: 30.25 inHg
# FPS FT-LBS PF
5 823 15.55 8.51
4 836 16.05 8.64
3 840 16.20 8.69
2 827 15.71 8.55
1 830 15.82 8.58
Average: 831.2 FPS
SD: 6.8 FPS
Min: 823 FPS
Max: 840 FPS
Spread: 17 FPS
Shot/sec: 0.1
True MV: 834 FPS
Group Size (in): 0.00
--------------------------------------------
Set: 4
Created: 02/13/16 08:43 AM
Description: 1.5 Turn
Notes 1:
Notes 2:
Distance to Chrono(FT): 1.50
Ballistic Coefficient: 0.031
Bullet Weight(gr): 10.34
Temp: 44 °F
BP: 30.25 inHg
# FPS FT-LBS PF
6 844 16.36 8.73
5 867 17.26 8.96
4 862 17.06 8.91
3 860 16.98 8.89
2 849 16.55 8.78
1 ERROR 2
Average: 856.4 FPS
SD: 9.6 FPS
Min: 844 FPS
Max: 867 FPS
Spread: 23 FPS
Shot/sec: 0.1
True MV: 860 FPS
Group Size (in): 0.00
--------------------------------------------
As you can see, the velocity doesn't really drop off until about 1.5 - 2 turns out. At ZERO turns out, there is definitely a gap between the striker and the SSG. It is approximately 3/4 of the width of the hammer pin... Anyway, some hours later, I shot this string:
Created: 02/13/16 11:12 AM
Description: 1.5 EFFICIENCY
Notes 1:
Notes 2:
Distance to Chrono(FT): 1.50
Ballistic Coefficient: 0.031
Bullet Weight(gr): 10.34
Temp: 56 °F
BP: 30.26 inHg
# FPS FT-LBS PF
61 845 16.40 8.74
60 844 16.36 8.73
59 850 16.59 8.79
58 845 16.40 8.74
57 ERROR 3
56 852 16.67 8.81
55 853 16.71 8.82
54 852 16.67 8.81
53 856 16.83 8.85
52 ERROR 3
51 851 16.63 8.80
50 845 16.40 8.74
49 852 16.67 8.81
48 853 16.71 8.82
47 850 16.59 8.79
46 855 16.79 8.84
45 856 16.83 8.85
44 843 16.32 8.72
43 854 16.75 8.83
42 851 16.63 8.80
41 848 16.51 8.77
40 846 16.44 8.75
39 849 16.55 8.78
38 848 16.51 8.77
37 848 16.51 8.77
36 846 16.44 8.75
35 853 16.71 8.82
34 848 16.51 8.77
33 853 16.71 8.82
32 846 16.44 8.75
31 861 17.02 8.90
30 850 16.59 8.79
29 853 16.71 8.82
28 ERROR 10
27 850 16.59 8.79
26 851 16.63 8.80
25 851 16.63 8.80
24 856 16.83 8.85
23 ERROR 3
22 854 16.75 8.83
21 855 16.79 8.84
20 858 16.90 8.87
19 850 16.59 8.79
18 ERROR 3
17 849 16.55 8.78
16 849 16.55 8.78
15 849 16.55 8.78
14 852 16.67 8.81
13 847 16.47 8.76
12 858 16.90 8.87
11 855 16.79 8.84
10 852 16.67 8.81
9 853 16.71 8.82
8 856 16.83 8.85
7 853 16.71 8.82
6 849 16.55 8.78
5 851 16.63 8.80
4 861 17.02 8.90
3 851 16.63 8.80
2 858 16.90 8.87
1 859 16.94 8.88
Average: 851.5 FPS
SD: 4.2 FPS
Min: 843 FPS
Max: 861 FPS
Spread: 18 FPS
Shot/sec: 0.0
True MV: 855 FPS
Group Size (in): 0.00
This string consumed exactly 1000psi of air, going from 3000psi - 2000psi (according to the rather low resolution ninja regulator's gauge) ... So with an average of 851.5fps (16.65fpe):
(16.65 x 61) / 1000 = 1.01565 fpe/psi ... This is the correct formula, right?
I would think I could clear 120+ shots per fill with the current 1050-1100psi set pressure, but I was hoping I would see the 1.5ish fpe/psi I see people reporting in the SSG thread... Would a higher set point likely yield better efficiency?
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You don't measure FPE/PSI, as it doesn't take into account the volume of the air reservoir.... I would be OK for your gun, but you can't compare to others.... To calculate the total volume of air used (at 1 bar), you multiply the pressure drop (1000 psi) by the reservoir volume in cu.in. (If you are using a 13 CI tank, multiply by 13) and then divide by 14.5 (psi per bar).... If you are using a 13 CI tank, that works out to (1000 x 13 / 14.5) = 897 CI of air used.... The total FPE is the average times the number of shots, so 16.65 x 61 = 1016 FPE.... The efficiency is the total FPE divided by the total air volume used to produce it.... (1016 / 897) = 1.13 FPE/CI.... If your tank is not a 13 CI tank, that number will be incorrect, of course....
A higher setpoint will yield a higher efficiency.... but if you go very far and then detune back to the velocity you have now, the velocity will INCREASE below the setpoint.... 1100 psi should be close for the FPE you have now....
Bob
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Lol on missing the volume of air, I don't know how many times have seen fpe/ci (never fpe/psi!) mentioned... Schoolboy error. Amateurism on public display! Thanks for taking the time to explain.
I am curious to see if I can achieve higher efficiency at a higher psi and knee... 1200psi should bring the knee to 900fps.
You know, just as I came to start getting a handle on this tuning thing, your SSG came along sent my head spinning! I should double check, but the knee should be at the same velocity with/without SSG, right? It seems I am reaching a knee now, as velocity out to 1.5 turns barely drops...
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It is possible that the SSG introduces a "false knee" if you plot velocity vs gap.... This is because as soon as you create a gap (for most SSG types) the velocity starts to drop off immediately as you increase the gap.... This does NOT happen on some types of SSGs, the velocity stays quite constant over the first turn or so (what you are experiencing), and that could be because you are on the plateau if you had no SSG in place.... or it could be some other factor.... At least one SSG design shows a slight INCREASE in velocity until the gap is about 0.020-0.040", and then a rapid decline.... I think the increase is because in that SSG type, where the hammer has to accelerate the guide at contact, and it is actually the end of the guide that opens the valve.... it takes a small amount of movement after first contact to get the guide moving at full speed....
The point is, that an SSG could well mask where the knee of the curve is, because it is not a linear device like a simple hammer spring.... This is obvious when you set one to have even slight preload instead of a gap.... the gun gets LOUD and uses a ton more air, as if you turned on a switch.... and when you back it out again to create the gap, the gun gets much quieter and uses a lot less air as soon as the gap appears.... To determine if you are still on the plateau or the downslope, you need to see what happens as you increase the preload (with no gap).... If the velocity continues to increase, you are on the downslope.... If it holds steady, you are on the plateau.... Since I tune my guns for the "knee", I increase the preload on the SSG until I no longer see a velocity increase.... Then when I back off the SSS to create a gap, as soon as I start to see the velocity decrease, I know I am on the knee of the curve.... If you can turn your SSG out 1.5 turns before the velocity drops, I would suggest that is where the knee STARTS.... From zero gap to 1.5 turns out, you are likely on the plateau.... If you need more velocity, your only solution (unless you hog out the ports) is more pressure....
Bob
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Since I tune my guns for the "knee", I increase the preload on the SSG until I no longer see a velocity increase.... Then when I back off the SSS to create a gap, as soon as I start to see the velocity decrease, I know I am on the knee of the curve.... If you can turn your SSG out 1.5 turns before the velocity drops, I would suggest that is where the knee STARTS.... From zero gap to 1.5 turns out, you are likely on the plateau.... If you need more velocity, your only solution (unless you hog out the ports) is more pressure....
Hmm. I am thinking that I need to thread another SSG. I do not have a lathe, only a rotary tool, a drill press and a bench grinder. For this reason, and the fact that there really isn't any danger of pinching on a 2400kt, I am still using the original SSG design. I have a TON of preload on my spring right now though. I think I tuned backwards. I already cut off the excess threads from the end of the one I have now, so I cannot back off preload any further.
You have once again powered a light bulb in my head. Looking at the photos of the first SSG you posted in your thread, I am assuming that is what it looked like tuned to the knee. The RVA looks to be turned out at least several turns already. Now, my understanding of tuning with an SSG (assuming I am looking for the "knee") is as such:
- Without the SSG installed, or at least with the stopping nut(s) and o-ring removed, and using a chronograph, determine the maximum average velocity (at least 5 shots) of a pellet at a given regulator set point.
- Install the SSG guide shaft into the gun and back the RVA out as far as possible.
- In my case, this is about 14.5 turns. The Challenger RVA (with the degasser tool threads drilled out to allow for the 3/16 SSG guide) stops engaging the spring at about 14.5 turns, but can't be removed until over 20 turns ... The spring rests against the internal threads of the end cap after 14.5 turns.
- Install the stop nut and o-ring on the guide shaft, turning the nut in until the o-ring is lightly sandwiched between the surface of the RVA and the nut.
- Determine velocity over 1-2 shots.
- Increase preload by turning the stopping screw in a fraction of a turn.
- Maintain zero gap by also turning the RVA in the same distance.
- I am assuming we want zero gap here, maybe even put a little load on the valve spring? I am winging it here...
- Determine the new, higher velocity over 1-2 shots.
- Repeat steps 5-7 until the AVERAGE velocity in step 1 is achieved.
- I stress average velocity here to avoid misreads. Until we get close, it isn't really necessary to get an average, right?
- Introduce a gap (0.020"-0.040") by backing off the RVA.
- Determine average velocity.
- If average velocity remains the same after introducing the gap, increase gap until velocity falls into the knee of the curve.
- If average velocity drops immediately, slightly increase preload on the spring until velocity does not drop with a gap of 0.020"-0.040"
- Any further velocity adjustments, say for lighter pellets or 5fpe indoor shooting should be done by increasing the gap with the RVA.
Does this all sound right? It does to me, though it wouldn't be the first time my logic was based on notions that get me so far out in left field I don't even realize my own team is at bat. Currently, there is a LOT of preload on on my spring. I was more concerned with making sure that I could still cock the gun with the RVA at 0 turns. It seems I should abandon that notion. If I don't like how far my RVA is sticking out of the rear, I can always cut a few threads off and readjust...
I don't expect this procedure it to make any difference to efficiency, but it would make for easier cocking, although I don't consider it to be difficult to cock now... I will also make sure to leave an inch or so of threads on the end of the guide shaft before increasing pressure. Once I am happy with things, I can cut off the excess again.
Since I am going to be tracking down the check engine light on my jeep today, I am looking at doing this tonight or tomorrow evening...
As far as getting more velocity, I am not really after that so much as I want to see if I can get better efficiency while staying on the knee of the curve. It would be interesting to see if I can get that number to climb when I am shooting from a 900fps knee... I also remember you mentioning at one point that enlarging ports and whatnot isn't really the way to go with .177, as it can actually decrease efficiency...
What would be a realistic goal for maximum efficiency (at the knee) for a 24" 2400kt in .177 with 10.34 JSB heavies? I want to keep knee velocity well under transsonic turbulence, so I don't really want to shoot much higher than 925fps. I know I can get the knee to that velocity with a 1400psi set point. I don't mind the ~850fps I am at now, but I would like to achieve something better than 1.13fpe/ci at the knee if I can... Lower velocities and lighter pellets are secondary concerns, and I understand that these velocities will increase below the set point if I am shooting on the downslope rather than the knee... When I am shooting at 5fpe indoors, I am fine with that. At those power levels, shot counts before even getting close to set pressure is ridiculously high anyway...
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Your tuning method should work.... I likely use fewer preload changes.... Note, I am nearly always tuning for the "knee" of the curve, with the ability to go lower by increasing the gap.... This requires I know where the knee is, before I start working on an SSG for that gun.... so I have a target for my maximum velocity....
1. Determine maximum velocity without SSG, ie where the "plateau" is for the pellet/barrel/pressure/porting combination you have.... and what the velocity is on the "knee" of the curve.... That will be your goal for the SSG with a small, but workable gap, where it is preventing hammer bounce as it should....
2. Try and figure a rough idea of the AVEARAGE cocking force as set up above....
3. Select a spring that when set up with preload of 4-5 lbs. (typical) will have an average cocking force the same or greater, and hopefully with a lower maximum cocking force....
4. Make a spring guide of the correct length to give you about 2-3 lbs. of preload, with enough adjustment (or the potential for adjustment) to exceed 5 lbs....
5. With the preload set as in #4, install the SSG and adjust to "no" gap.... The velocity will almost certainly be below maximum.... Confirm by adding some preload with the gap adjuster.... The report, and velocity, should increase....
6. Increase the preload on the spring guide at least 1 turn (I typically use 0.1" increments).... About 1 lb. more preload per step would be a good choice....
7. Set to no gap, check velocity.... Add some preload / negative gap - you should notice a large increase in the report, and some extra velocity.... Back off to 0.020-0.040" gap and record velocity....
8. Repeat steps 6 & 7 until you can achieve, or nearly achieve, your maximum velocity when preload (ie no gap) is present....
9. Set the gap to minimum, record the velocity, increase the gap in small increments, and record it again.... I like to see the velocity "just tickling" the plateau with no gap....
10. Check your efficiency and velocity with various gaps, and determine what adjustment meets your requirements....
If at any stage along the way you hit coil bind, you need a longer, softer spring, and more room for it behind the hammer.... The above is just one way of tuning an SSG....
Bob
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Hi Bob,
It seems I am on the right track then! All right! I am officially calling myself "intermediately skilled" ... no longer a newbie!
Anyway, it seems I was editing my post while you replied to it. I will quote myself below ...
What would be a realistic goal for maximum efficiency (at the knee) for a 24" 2400kt in .177 with 10.34 JSB heavies? I want to keep knee velocity well under transsonic turbulence, so I don't really want to shoot much higher than 925fps. I know I can get the knee to that velocity with a 1400psi set point. I don't mind the ~850fps I am at now, but I would like to achieve something better than 1.13fpe/ci at the knee if I can... Lower velocities and lighter pellets are secondary concerns, and I understand that these velocities will increase below the set point if I am shooting on the downslope rather than the knee... When I am shooting at 5fpe indoors, I am fine with that. At those power levels, shot counts before even getting close to set pressure is ridiculously high anyway...
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All I can suggest is trying different combinations of preload and spring length.... It sounds like you are pretty close to the plateau with your current setup, that may be the reason you can't improve your efficiency without further reducing the velocity.... More pressure may be required....
Bob
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1.48404154 fpe/ci!!!
I'm just gonna say it:
BITCHIN!!!
Okay, now that we have that out of the way, going up to 1200-1250psi (set point range) really made a difference! With the SSG uninstalled (or with just the stop nut removed, it didn't make any discernable difference), the plateau is at about 920fps with JSB Heavies. I think the highest was 926fps. Anyway, the maximum velocity I could achieve with zero gap was about 900fps. Once I introduce gap, the velocity starts to fall right away, as suggested before. Now, with the velocity adjuster turned all the way in, and with about .02" gap (between 3-4 flats on a 10-24 nut), I am averaging 884.8fps, which should put me in the well into the knee. I will report later on which way the spread goes below set pressure... Anyway, I shot a string from 3000psi to 2500psi, stats as follows:
(http://i1066.photobucket.com/albums/u404/appye/1200PSI.png) (http://s1066.photobucket.com/user/appye/media/1200PSI.png.html)
Average: 884.8 FPS
SD: 4.9 FPS
Min: 874 FPS
Max: 894 FPS
Spread: 20 FPS
True MV: 885 FPS
This was looking PESSIMISTICALLY at the pressure gauge. I likely could have included another 3-5 shots in the string ...
I am not sure what "True MV" is, and I am still trying to wrap my head around standard deviation...
Anyway, if I am using your formula correctly, I used 448.275862ci of air, achieving a total of 665.26fpe, so 665.26/448.275862=1.48404154 fpe/ci! I may try 1400psi at some later date, but so far I am extremely happy with this vast improvement! These are the numbers I was hoping for when I first saw the SSG!
And yeah! I made a chart! Bob, what application are you using to make yours? It took me a few minutes to figure it out in libreoffice, but it still doesn't look as cool as the ones you make...
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Efficiency of 1.5 in .22 cal at over 30fpe. Well done, sir!
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Huh? No this is .177 at about 18fpe... JSB Heavy 10.34gr!
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Oops, sorry! I was looking at it quickly on my phone. That being the case, it's no less impressive in my book. :D
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I use Excel for my spreadsheets and charts.... and CONGRATS, BTW !!!
Bob
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Thanks again for the tech support, all!
Here is a string I shot yesterday when I noticed that my pressure was at around 1400psi...
(http://i1066.photobucket.com/albums/u404/appye/1400-1000.png) (http://s1066.photobucket.com/user/appye/media/1400-1000.png.html)
I would call shot #7 a fluke, I am not sure what is going on with the spike after shot #21, and shot #25 didn't register on the chronograph.
If I remember right, with the shims set up as they are now, the regulator outputs ~1200psi when the bottle is at 1500psi, and at 1250psi when the bottle has 3000psi. These readings were taken from the benjamin hand pump, the ninja bottle gauge, and a separate, larger 3000psi gauge I bought to test regulator output pressure. Below set pressure, all three gauges seemed to agree with one another quite closely. Above set pressure, the bottle and pump seem to agree pretty consistently all the way up to 3000psi.
So I started at ~1400psi. It was at about 1250psi at shot 12 or so. Again, this is looking at the low resolution ninja gauge, so it's hard to tell for sure ... I guess I am splitting hairs at this point, but with the dropoff being so gradual after that, this should put me right at the sweet spot of the knee, right? Of course, this is just one string ...
There is that little spike after shot 21, but I was well under set point by then, so I don't think that is indicative of being on the downslope... I would be comfortable shooting down to 1000psi with this setup, at least offhand. Staying above set point, I should have a total shot count (18fpe) of around 130 per fill. Not bad!
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Getting over a ton (literally) of energy from a 13ci tank is a fine result. Superbly done!
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Unfortunately, I think you are confusing "knee" and "downslope" with the shape of your shot curve, those terms have nothing to do with the velocity plot in your last post.... They mean how the velocity relates to the hammer spring preload AT CONSTANT PRESSURE....
If you think that your setpoint pressure was reached at around shots 12-15, since I see no sign of a slight increase in velocity at that point, that would indicate you are likely operating on, or close to, the plateau of the curve at 1200 psi.... If you were on the downslope, the velocity would increase dramatically below the setpoint.... If on the knee, it should increase very slightly, or the shot string should at least extend below the setpoint for a few shot before the velocity drops off....
Bob
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Getting over a ton (literally) of energy from a 13ci tank is a fine result. Superbly done!
Huh! I hadn't thought of it that way before. 2,340lbs total! I'm gonna start telling people that!
Unfortunately, I think you are confusing "knee" and "downslope" with the shape of your shot curve, those terms have nothing to do with the velocity plot in your last post.... They mean how the velocity relates to the hammer spring preload AT CONSTANT PRESSURE....
If you think that your setpoint pressure was reached at around shots 12-15, since I see no sign of a slight increase in velocity at that point, that would indicate you are likely operating on, or close to, the plateau of the curve at 1200 psi.... If you were on the downslope, the velocity would increase dramatically below the setpoint.... If on the knee, it should increase very slightly, or the shot string should at least extend below the setpoint for a few shot before the velocity drops off....
No confusion, really! The post was supposed to show what is happening once I transition below set pressure. I was looking for thoughts on whether I was closer to the plateau or the downslope. I thought I had included that thought (being on the plateau) in my last post. I guess I edited it out... I tend to read over long posts like that and start rearranging things before posting.
I am still confused about the whole knee/ssg relationship though ... I was hoping to see the string extend past the set point by a few shots, and was actually more worried I was going to see an increase, since I am so far below the plateau (920fps) with no SSG installed and everything else the same... I am definitely at this gun's highest power level with an SSG and a small gap though. Is this the "false knee" you were taking about before? The graph suggests that I am still well up on the plateau, and set pressure is reached at shot 10... Again, this is just one string though, and averages over several strings would be more accurate.
If I want to be over 900fps with an SSG at this set point, I would either need a heavier hammer or spring. I did remove material from the hammer when I was hunting down drag a couple weeks ago ... I think I am going to leave well enough alone for now though. I could try a stiffer spring, but I don't want the cock to be uh ... any harder ... um yeah...
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Judging by the shape of that shot string, I would say that you aren't going to get much more velocity without a big decrease in shot count at the pressure you are running....
Bob
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Yep. I am not really after that so much as I am after an understanding of how this works... Why is it that having an SSG lowers where the knee is? Without the SSG installed, the plateau is at around 920fps. If I were to dial that down to 885fps (the same velocity as the plateau I am shooting at now) I would likely be well into the knee of that curve, right?
As it appears that I am indeed on the plateau, I may shoot another string this evening at something less than max power, both to find the "sweet spot" (where velocity stays consistent a few shots below set pressure), and to see just how efficient this really is if I am truly tuned to the knee... I would expect even better numbers.
Aside, I am waiting until this evening because I find that this Caldwell Chronograph (with the infrared light kit) is much more consistent if I shoot in the dark with no artificial lighting, be it florescent, incandescent, whatever. Sub optimal lighting definitely played a factor in the wide ES I was pulling my hair out over a few weeks ago.
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It has not been my experience that the SSG lowers the knee, but it can certainly decrease what you SEE as the plateau and knee.... I found that increasing the preload gave gradually more velocity WHEN OPERATING WITHOUT A GAP, and eventually you could get back to where your plateau was without the SSG.... however, if you had less preload that that, trying to get back to your original velocity required that you reduce the gap to zero, and then the efficiency goes into the dumper.... Once you get the velocity with preload back to where your original plateau was, then backing out until you have a small gap should put you back on the original knee.... but with improved efficiency....
Bob
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Well, I guess I am satisfied with this gun, as I have been spending a lot more time SHOOTING it rather than tuning it! I guess that was the whole point to begin with!
Anyway, I picked up a cheap $1 spirit level, took it apart and epoxied the tube to the bottom of my aperture sight. What a difference it made to my group sizes! Before, even with a scope, it was difficult to get below 1" (10 shots) at 50 yards, but now 1/2" is pretty normal! I was beginning to worry that it was my barrel, and was starting to think about L/W and the like, other "premium" barrels ... Now I know it was me all the time!
Here is what the level looks like ...
(http://i1066.photobucket.com/albums/u404/appye/IMG_0540.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0540.jpg.html)
Here is a DIY front sight idea I am playing with. I have been banging around with this one for a week or so. The hole is 7/64" if I remember right, but I will likely go a bit smaller in hopes of getting a little more precision. A 1/16" hole was too small for me, so it will be somewhere in between. I am also thinking of having two holes stacked on top of one another, one for close range and one for further out... I definitely prefer looking through these over the standard post. I like to shoot with both eyes open, focused on the target. I know, this sounds like blasphemy to some folks.
(http://i1066.photobucket.com/albums/u404/appye/IMG_0541.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0541.jpg.html)
I also like to shoot left and right handed...
This is a fairly typical group (8-10 shots) at about 55 yards or so ... This is bag rested and scoped, shooting full power with the JSB Heavies picked straight from the tin. I center the level on every shot. This one measures .52 CTC ...
(http://i1066.photobucket.com/albums/u404/appye/IMG_0539.jpg) (http://s1066.photobucket.com/user/appye/media/IMG_0539.jpg.html)
With the scope removed, my groups are generally about an inch or so, also an improvement from before... Again, I hope to tighten that up a little with a slightly smaller front sight.
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Hi All,
I figured I would just ask here ... I have been loving this gun, especially since I put the level on the back of the sites. It is really, really accurate! The SSG made it efficient as humanly possible, and I am happy with every aspect of the gun.
... And now I want to modify it again.
Where do I start at getting a longer main tube? I want to enlarge the plenum and further increase efficiency or maybe even bump it up into the 20+ fpe range. I briefly looked around the internet and all I find for 2260 main tubes are those that have the roll stamped lettering. I would prefer it to be either completely blank or with only the laser embossed lettering. I also want a drop in part that I don't have to machine, other than drilling the extra valve retaining holes. Would a discovery tube work? Is there anything I can order from Crosman that will fit the bill? I am hoping to keep the ~1200psi reg setting, but I may see what I can get with ~1400psi
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Don Cothran makes excellent 22xx stainless pcp tubes in various sizes. I also see Roy at Mountain Air sells various sizes.
I'm running a Don Cothran 2250 tube at 1500 psi getting 23 fpe with 18 grain JSB's.
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Baker Airguns sells Disco tubes for $20 plus shipping.
Gipper
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I like the baker prices. Would a disco tube already have all the correct machining, ie, breech mounting holes, transfer port in the right place, etc? I guess I could either plug the gauge hole or of course put a gauge in there.
I can't tell if the "Tubes for Crosman 2200 Series (https://www.bakerairguns.com/product/tubes-for-crosman/)" tubes on that site are roll stamped or not. It looks like the 16 5/8" tube would just about double the plenum size.
Of course, a disco tube would what, quadruple it? Anyone know the plenum sizes of these tubes in cc or ci, assuming a regulated HPA setup? I read somewhere that at some point, plenum size can be too large for a regulator to maintain consistent PSI ... I am using a Ninja HPA regulator, and this gun is .177 if it makes any difference...
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Plenum too large? Much ado about nothing. Not saying the effect isn't present but it is of no practical consequence. The idea is, if very little air is used, there may not be enough pressure drop to allow the regulator's seat to open and top off the pressure. Therein lies the answer. If the pressure barely dropped, the next shot will not be starved of air. Also, a regulated rifle set up properly, running near the knee of max velocity, will hold a tight ES just as an unregulated one will do over a wide pressure range. A super tight regulated pressure isn't as critical as it might seem from intuition.
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Yes the Disco tube would be ready to go...No drilling required.
Gipper
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Plenum too large? Much ado about nothing. Not saying the effect isn't present but it is of no practical consequence. The idea is, if very little air is used, there may not be enough pressure drop to allow the regulator's seat to open and top off the pressure. Therein lies the answer. If the pressure barely dropped, the next shot will not be starved of air. Also, a regulated rifle set up properly, running near the knee of max velocity, will hold a tight ES just as an unregulated one will do over a wide pressure range. A super tight regulated pressure isn't as critical as it might seem from intuition.
Makes sense to me!
Yes the Disco tube would be ready to go...No drilling required.
Methinks a new Disco tube is going to be arriving at my doorstep in the near future!
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ORDERED!!!
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I am in the process of building the same rifle, but mine started life as a Disco. Mine is together but I need to make a forearm for it. I went with an RAI AR15 buttstock setup, 850 PSI Ninja bottle and the standard QB bottle block. I used the stock hole positions but added a 10/24 set screw on top and back further from the end of the tube to add additional safety. The position of the top set screw will also allow me to drill for a pin and use that screw to hold the pin if I decide to up the regulated pressure later on. I am waiting on a breech riser from Baker and need to add an LDC. I also removed the gauge and block and replaced with an aluminum piece drilled out to 5/8". Valve is stock for now as far as I know (bought used), I have the poly tube transfer port and I chopped the barrel to 18". As she sits she is shooting 8.4 JSB's at 755fps. When finished I would like to add at least an additional 100fps to that
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...850 PSI Ninja bottle and the standard QB bottle block...
So you have your bottle hanging way out in front of that long disco tube?
I have been running mine at 1200psi, and getting about 900fps with the 10.34 grain jsb's (24" barrel) ... Depending on what I have to work with and what efficiency numbers I can achieve, I am hoping to get 900-950 with the monsters or even the beasts. I dunno how possible that is without increasing pressure beyond 1400psi, which is as high as I want to go with the 1.8k burst disks. Maybe 1500psi. I don't want to blow efficiency out the window though, so I plan on staying on the knee of whatever curve I get out of the pressure I ultimately decide on.
Anyway, &^^&. I did not think of this. Since I got a disco tube, I am going to have to get a gauge block and adapter, or at least a plug. Once I have the part in hand, I am going to see how feasible it is to turn the bottle around so it feeds the gun through the guage port.
Does anyone know of a larger bolt handle I can find? I suppose I could find the right thread hardware store bolt and wrap something around it... Cocking would be much easier if I could fit more than one finger around it.
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...850 PSI Ninja bottle and the standard QB bottle block...
So you have your bottle hanging way out in front of that long disco tube?
No I cut my tube back. I am not sure exactly how long it is as I simply made sure I had enough tube to utilize a crosman forearm if I wanted to instead of making one myself and enough tube to cut it again if I managed to screw it up!! As it is now the 18" barrel extends about 1/2" beyond the bottle. The breech riser should give me enough room to do a a shroud or LDC. Your numbers are more inline with what I am after and I figured a higher reg set point was going to be needed but I built this rifle with parts I had on hand. Max power for me is not the main goal but a nice balance of power and shot count. I started this project after buying a PROD that I have been less than thrilled with in terms of shot count. Small tubes are very unforgiving when it comes to balancing efficiency and power...at least for me. The larger capacity bottle allows me to be less than perfect in my tune and still have acceptable shot counts and Power. If I could get 40 or so shots out of a fill in the 18-20 FPE range I would be more than happy.
Brian
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Your numbers are more inline with what I am after ... The larger capacity bottle allows me to be less than perfect in my tune and still have acceptable shot counts and Power. If I could get 40 or so shots out of a fill in the 18-20 FPE range I would be more than happy.
I see ... I am able to achieve the numbers I have now, largely because of the longer (24") barrel I think. Also, you are mentioning 40-50 shots at 18-20fpe. I am guessing you are unregulated then?
The regulator plays a huge part in shot consistency... Currently I am getting around 130 shots at 18fpe (jsb 10.34) on a fill before velocities start to drop. I am hoping to either increase my shot count or power. Probably going to go for power first to see what I can get, maybe even see what 1400-1500 psi can do with the larger plenum. I guess I am going to be running through more tins. I go through FAR more pellets when tinkering than I do when the gun is "done" ... I have been working on the same 500 tin of heavies since March-April (bought a foreclosed house in the mountains and have been brushcutting) and still haven't finished it. This will change in a hurry! The brushcutting has to get done first though. After all I need to actually have a house to keep my guns in.
Once I have the parts, I am going to see if I can make 13.43 Monsters (maybe even 16.2gr beasts!) go 950fps, and with any accuracy. Do I NEED the power? *(&^ no! Do I WANT the power? YES! One can dream ...
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Your numbers are more inline with what I am after ... The larger capacity bottle allows me to be less than perfect in my tune and still have acceptable shot counts and Power. If I could get 40 or so shots out of a fill in the 18-20 FPE range I would be more than happy.
Also, you are mentioning 40-50 shots at 18-20fpe. I am guessing you are unregulated then?
My Ninja bottle is regulated at 850PSI. I just have not done a shot count on it at its current reg setting so have no idea what to expect at this point. Mentioning 40-50 shots at those power levels was just a ballpark figure of what I would be content with, not an estimate of what I think I will get.
As far as the gauge block and gauge goes I would eliminate them if you can. There is no need for the gauge and the block itself can be a restriction at higher power levels. I am also fascinated with the new heavy .177 pellets available and plan to build a rifle to toss them heavy suckers at higher speeds but have a Bam B50 I am going to use for that endeavor.
Brian
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My Ninja bottle is regulated at 850PSI. I just have not done a shot count on it at its current reg setting so have no idea what to expect at this point. Mentioning 40-50 shots at those power levels was just a ballpark figure of what I would be content with, not an estimate of what I think I will get.
As far as the gauge block and gauge goes I would eliminate them if you can. There is no need for the gauge and the block itself can be a restriction at higher power levels.
I forgot about your 850psi bottle. If you are just shooting at 755fps, you should get hundreds of shots, assuming a 3000psi fill and your bottle is the typical 13ci... I am not sure if you will be able to achieve 850fps with 850psi though. I know I was able to touch the high 800's with 1000 psi using the standard 2400kt tube, but it was not as efficient as the 1200psi I eventually went with.
As to eliminating the gauge block, I am unsure if that is possible. Something needs to seal off that hole at least, and I really like the idea of mounting the bottle from it. I am glad you mentioned the restriction though. I was looking around and it seems that the PROD "GAUGE PORT ASSEMBLY" (1700-104) fits into a disco tube, and is much more open. I wonder what the almighty Bob would say ...
...And here I was originally thinking I was gonna get away with twenty bucks and a tube swap! Let the nickeling and dimeing begin.
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No doubt costs can add up but the beauty is you can do it in stages and enjoy the rifle in the mean time.
Brian
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Did you receive your parts from Baker yet? Any progress?
Brian
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Well, I got the tube, but forgot all about the gauge pet assembly. Since I am going to see what I can get tuning for power, I am going to order the p-rod part from crosman.
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Well, I got the tube, but forgot all about the gauge pet assembly. Since I am going to see what I can get tuning for power, I am going to order the p-rod part from crosman.
Just a heads up. I talked to crosman last week. The PRod gauge block is back ordered, and will be for a couple of weeks atleast. That is what i was told any way. If it is different now give us a heads up as i need it as well.
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Hmm... I just ordered the port and adapter from "archery" airguns. I hope this isn't going to be some $&%* where they are waiting on crosman. I wanna rebuild my gun!
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Lol ... I got moderated! Me and my dirty mouth!
Anyway, it seems all parts are being shipped. I also went with the "tank top adapter" at mac1 because it looks like the existing ASA would otherwise butt right up to the trigger guard. My only worry at this point is getting the bottle the right height in relation to the tube. In my existing config, it is just a few millimeters below the tube, and I am hoping to duplicate that, at least closely.
I am pretty sure I have all adapters, etc. on the way, and I hope to start (re)building sometime this week...
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Lol ... I got moderated! Me and my dirty mouth!
Anyway, it seems all parts are being shipped. I also went with the "tank top adapter" at mac1 because it looks like the existing ASA would otherwise butt right up to the trigger guard. My only worry at this point is getting the bottle the right height in relation to the tube. In my existing config, it is just a few millimeters below the tube, and I am hoping to duplicate that, at least closely.
I am pretty sure I have all adapters, etc. on the way, and I hope to start (re)building sometime this week...
That i awesome!Let us know how it goes. I Hope everything goes nice and smoothly.
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Hi all,
Since I am further modifying this gun, if you after interested, I have decided to create a new thread on it:
http://www.gatewaytoairguns.org/GTA/index.php?topic=113189.0 (http://www.gatewaytoairguns.org/GTA/index.php?topic=113189.0)
I hope some you experts can take some time and provide your thoughts!
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Hi all,
Since I am further modifying this gun, if you after interested, I have decided to create a new thread on it:
http://www.gatewaytoairguns.org/GTA/index.php?topic=113189.0 (http://www.gatewaytoairguns.org/GTA/index.php?topic=113189.0)
I hope some you experts can take some time and provide your thoughts!
I hope everything ends up working out.