Pneumag frustration...

[Loneassassin]

So I went paintballing yesterday for what could possibly be my last time until next year. Anyway, to make a long story short, I wanted to make the day count and just have a good time altogether.

Well, first off, my E-cocker was acting schizophrenic (I now know why, and I'll solve that over the winter.) So I moved on to my Pneumag. Just a little background: when I first set it up, I had problems with the ULT not resetting fast enough. I'm running 4 shims in the ULT then and now. I recently upgraded to a Crossfire hpa reg and now I seem to have the opposite problem - it RTs like a mofo.

I've found that I can tune out some of the RT effect by upping the Lpr pressure. However, that's usually when tuning off of a ~1800psi fill from my scuba tank. Yesterday I was getting 3000+ fills all day from the field, and the thing was going 20bps I'd guess. The problem, other than shooting WAY to fast was that it was chopping like crazy, and this is with a Prophecy. The level 10 is tuned, but could be a little more sensitive if get a new bolt spring.

How do you RT guys shoot so fast without chopping? I don't want to shoot that fast, but more importantly, I don't want to chop. I want only one shot per pull, but still walkable. Should I try removing a shim from my ULT? Basically, what else can I do to my setup to make the thing true semi without getting to the point that it won't keep up with my trigger walking? It seems to be much worse when my tank is at 3000 psi or above. (Which is kind of where you want it to be considering it ain't that efficient.) Thanks for any help!

[redlaser666]

If its a pneumag, you can try a standard RT on/off or take out 1 or 2 shims from the ULT

[TwilightG]

+1 for RT on/off. Also, make sure you have a sufficient gap between the sear "leg" and the ram. Should be close to 1/8".
Sounds like the ULT is bouncing off the ram before the ram has time to fully reset (kind of just speculating on this one)
this could cause an occasional chuff due to short stroking leading to barrel breaks which could very well be the issue and not an actual chop.

speaking of which, you can still short-stroke a pneumag if the MSV is only partially opened on a trigger pull. adjust your trigger stops to optimize the trigger pull. same goes for the trigger pin... if it's too short, you won't move the MSV arm far enough, too long and you're potentially making your trigger pull too long (which can also lead to short stroking)

[GEE TEE]

I would put the extra RT'ing down to a pressure increase in the output from the Crossfire reg.

Most HPA bottle regs vary in output. I have 4 tanks here that go from 780psi to nearly 900

[Loneassassin]

+1 for RT on/off. Also, make sure you have a sufficient gap between the sear "leg" and the ram. Should be close to 1/8".
Sounds like the ULT is bouncing off the ram before the ram has time to fully reset (kind of just speculating on this one)
this could cause an occasional chuff due to short stroking leading to barrel breaks which could very well be the issue and not an actual chop.

speaking of which, you can still short-stroke a pneumag if the MSV is only partially opened on a trigger pull. adjust your trigger stops to optimize the trigger pull. same goes for the trigger pin... if it's too short, you won't move the MSV arm far enough, too long and you're potentially making your trigger pull too long (which can also lead to short stroking)

Thanks for all the responses guys! As to your response, the gap between the sear leg and piston is about 1/8," so I don't think the problem is there.

I left the lever on my MSV-2 full length, and have the trigger pin hitting it close to the top. Would changing where the pin hits the lever (by shortening the lever and repositioning it) for less leverage help the problem? The trigger is very, very soft, perhaps too soft as it is.

Also, wouldn't an RT on/off exacerbate the problem, by increasing the reactivity on the sear? As a start, I might just see what happens when I remove a shim or two from the ULT.

[TwilightG]

Thanks for all the responses guys! As to your response, the gap between the sear leg and piston is about 1/8," so I don't think the problem is there.

I left the lever on my MSV-2 full length, and have the trigger pin hitting it close to the top. Would changing where the pin hits the lever (by shortening the lever and repositioning it) for less leverage help the problem? The trigger is very, very soft, perhaps too soft as it is.

Also, wouldn't an RT on/off exacerbate the problem, by increasing the reactivity on the sear? As a start, I might just see what happens when I remove a shim or two from the ULT.

the longer the msv leg, the longer the trigger pull length. it's still possible that the msv is being short stroked due to this (a magnet mod from cyberave68 or mag79 helps A LOT)
alternatively, shortening the leg makes the pull shorter, but heavier (still very soft though, just different)... in fact you may not even notice the difference in trigger pull weight

as for the RT exacerbating the problem, I don't think it would. The force necessary to push in the on/off pin on an RT is much more than the ULT so I think it'd be less prone to bouncing off the ram (if this is even the cause of the problem)

removing shims from the ULT should make it less sensitive though.

[Loguzzzzzz]

The pressure in your tank should have nothing to do with this as long as your tank regulator is functioning properly. Check the output pressure on your tank reg. I have had Crossfire regs go bad at which point my valve was seeing the actual tank pressure and not the 850 psi that a Crossfire is set to. Check that first.

[Loneassassin]

The pressure in your tank should have nothing to do with this as long as your tank regulator is functioning properly. Check the output pressure on your tank reg. I have had Crossfire regs go bad at which point my valve was seeing the actual tank pressure and not the 850 psi that a Crossfire is set to. Check that first.

I will check that - though the reg is practically new; I wouldn't expect it to fail quite yet. Plus, I would expect the Lpr to start having problems too.

The reg is supposed to output at 850psi, and the flow rate is infinitely better than my Myth reg was at the same output. I had a hard time with chuffing with the Myth - with the Crossfire reg I have a hard time holding the RTing back, lol. When it's not RTing/double/triple firing, it is as easy to walk as any electro.

[Loneassassin]

Update: I don't know if anyone is interested, but I finally got around to troubleshooting my Pneumag after some of your advice. (I figure it can't hurt to share tuning knowledge)

I first tested the output of my Crossfire reg as per Loguzzzzzz. Output was a solid 815ish psi according to my gauge, so that wasn't the problem.

Next, I removed a shim from my ULT for a total of 3 and aired her up. The gun was still bouncing but not quite as bad. So I tried upping the Lpr pressure. Bounce got better. Turned it up a bit more, and finally I couldn't get it to bounce no matter what.

Finally, I had to do a trigger walking test with paint. AT LEAST 15bps consistently, no chuffing, chopping, or stuttering of any kind.

I'm a believer once again...

Happy Thanksgiving!

[GEE TEE]

Nice one - would be nice to see a shooting video posted up

A pneumag build is next on my Mag projects list

[Loneassassin]

I'll try to make a vid over the holidays. I can't shoot it where I live right now because I'm right in the center of town - but I'll be visiting my folks around Christmas and they live up against the wilderness, lol. I've got an old video but it doesn't do it justice; I've never had it shooting quite like this. Too bad I've got 7 more months of winter to look forward to...

I think the real problem was that the sear was bouncing off the ram piston, because the lpr pressure was enough to trip the sear, but not quite enough to hold it back until I intentionally let go.