Pneumags and barrel breaks

[longi]

I 've been reading a lot lately about Pneumag users consistantly having paint breaks in the last 2 inches of the barrel, myself included. It occured to me that the Pneumag internals on the average Pnuemag runs at around 60-80 psi and if the ULT is installed 30-40 psi. The Gforce frame also works at around 30-40 psi. I have a Gforce frame and I still encounter ball breaks. So, I thought maybe the internal working pressure of the internals are causing drop off around every 1-10 shots fired, enough drop off that ball to ball collision in the barrel occurs causing a barrel break. I don't know how to calculate/predict how much air would need to be drawn away from the main valve (in psi) before drop off would occur and barrel breaks would in turn occur.

As an example my setup using a standard RT/Emag on/off pin would need say 65 psi to trip the sear. My Tank reg is set to 800 psi and my muzzle velocity is around 280 fps.

I think the internal of the frame are "stealing" enough air to cause this. How do I calculate/predict how much air would need to be "stolen" from the main valve to cause such a large amount of drop off?

[Hilltop Customs]

pressure drop would also be consistent shot to shot, as the same volume is required each shot for the ram. It shouldn't have enough variation to cause extreme swings in velocity(enough to cause ball collision at the tip of the barrel).

Shortstroking would be a more likely culprit, but I dont think it would be ball on ball collision for the simple fact that there should also be collisions right outside the tip of the barrel...which I dont think people are seeing?

[Dend78]

that would be nuts to see a ball on ball outside the gun, not the gay porn ball on ball either guys

but yeah drop off should occur on every shot not just one out of 10 if that were the case

[Pneumagger]

I'm sure it's short stroking. I have'nt experienced this problem with any EP mags.
I have experienced this with regular pneumags, especially before they are fine-tuned.

Also, it's simply not drawing enough air to affect the flow to the marker.
Were talking about 50psi of air occupying a 3/8" ram throughout 1/4" travel. (.0276cuin of air)
I think an AIR valve has something like .55cuin of charge volume.
So the pneumatics are demanding an additional 5% performance from the marker's air delivery.

If you're shooting fast enough to cut into that 5% drain then that's quite feat. Odd's are you've got bionic fingers.

[gunangel]

I think it's honestly due to the lvl 10, which i guess could be considered short stroking.
during rapid firing (10 bps +) i never hear the lvl 10 engaging completely and once in a while i see a ball roll out the barrel. my theory would be that the level 10 partially engages, but another cycle happens with the ball not clearing all the way pushing the ball partway down the barrel leaving the next ball to go on through and smack right into it. I see breaks in a variety of lengths, at the breech, at the bolt, and in the barrel. i've never seen a break happen anywhere near the breech with my rt valve (used with a halo). i would be interested in hearing other thoughts tho

[Hilltop Customs]

The problem with the lvl 10 is it amplifies the one downfall of the lvl 7 mag(or mags in general), shortstroking/riding the trigger. Since lvl 10 is pressure sensitive(it relies on the balance between the bolt spring and dump pressure to "pinch" the balls) ANY short stroke will result in a much greater effect than a lvl 7 short stroke since the balance shuts off air flow faster.

With a pneumag, too quick of pull results in the ram not fully empting of pressure and the on/off not fully opening(the exact same thing that happens when you ride the trigger in a normal mag).

Best thing to do is add a post travel sear stop. It limits the excess volume of the ram. Its also good to limit pre-travel too by adjusting the ram postion or the length of the ram rod( you want the piston to be nearly fully inserted into the ram when at rest). This all just limits the volume of pressurized air required to opperate the ram. Less volume means less air needs to pass through the 3 ways limiting orfice.

Smaller volume that needs to pass through the 3 way = faster a pneumag can cycle = less chance of short stroking during rapid firing

Or you could just go ep and have complete control of the dwell

sorry about spelling, stuck in IE and dont feel like opening word on this slow computer.

[longi]

I fitted a sear stop last month but I haven't as yet had chance to try it out with paint. I just changed the MSV-2 geometry around, adjusting the MSV-2 angle around. It's lost a touch of feel but it's dramatically increased the rate of fire! Interesting trade off! Off the subject there a bit, but I thought I'd add that in.

Would there be any way you could mechanically control the dwell without the use of electronics? What I need is something to shut off the air once the trigger is pulled allowing the the acuator to reset even though the trigger is still held in, and will not cycle again before the trigger is fully released further reducing short stroking.

[Hilltop Customs]

nothing out there that mechanically does it at the moment, but y0da900 has a really neat mechanical dwell valve over in the open source thread: http://automags.org/forums/showthrea...wpost&t=235965

[longi]

It's just begging for someone to make such a device. It's an exciting prospect alright, if it could be incorporated into a Pneumag that would be just fantastic..

[cyberave68]

I'm sure it's short stroking. I have'nt experienced this problem with any EP mags.
I have experienced this with regular pneumags, especially before they are fine-tuned.

I agree with Pneumagger, i had the same problem with some of the ones i built for other people. With what i was testing i thought that the return pressure on the trigg wasnt strong/fast enuff. It seemed to me that the MSV valve never got a chance to close all the way in rapid fire. Thus causeing a short stroke. I figured out a way to increase the return pressure by useing small magnets set up inside of the frame opossiong each other. It seemed to help alot but i cant say it is a perfect solution. Works well for me and also knowing the spring in the MSV is TINY!!! See if you cant fing a way to add something in there to assist the return force pushing on the trigg as is may help...

Just my .02
Cy

[longi]

I agree with Pneumagger, i had the same problem with some of the ones i built for other people. With what i was testing i thought that the return pressure on the trigg wasnt strong/fast enuff. It seemed to me that the MSV valve never got a chance to close all the way in rapid fire. Thus causeing a short stroke. I figured out a way to increase the return pressure by useing small magnets set up inside of the frame opossiong each other. It seemed to help alot but i cant say it is a perfect solution. Works well for me and also knowing the spring in the MSV is TINY!!! See if you cant fing a way to add something in there to assist the return force pushing on the trigg as is may help...

Just my .02
Cy

Already done it, i've just had had time to try it out. I still may have to move the magets around to find the best position for them.

[snoopay700]

I never had this problem with my pneumag, news to me.

[longi]

I never had this problem with my pneumag, news to me.

Interesting, How is yours set up? ie...Do you use magnets, trigger stops, how is the MSV-2 geometry setup? Any info would be greatly aprreciated.

I was even thinkig of drilling a small hole in the side of the actuator to see if I could get it to cycle faster. The hole position would be critical. I was thinking of drilling it somewhere where on the side. The ram o ring would need to pass over it before it reached it's full extension so it wouldn't run out of energy too early. Drill the hole too low and it probably wouldn't work at all. It would be a bit like reversing the operation of the Level 10 bolt. What do you guys think?

[snoopay700]

Interesting, How is yours set up? ie...Do you use magnets, trigger stops, how is the MSV-2 geometry setup? Any info would be greatly aprreciated.

I was even thinkig of drilling a small hole in the side of the actuator to see if I could get it to cycle faster. The hole position would be critical. I was thinking of drilling it somewhere where on the side. The ram o ring would need to pass over it before it reached it's full extension so it wouldn't run out of energy too early. Drill the hole too low and it probably wouldn't work at all. It would be a bit like reversing the operation of the Level 10 bolt. What do you guys think?

I've got it so it partially opens up the msv-2 where if you hold the trigger you get a shot you hear air leaking then a second or two later it shoots another shot, and i have the magnet mod inside it. I can take pictures tomorrow if you'd like, today i'm a bit too busy around the house and then going out with my friend.

[Mongoose]

that would be nuts to see a ball on ball outside the gun, not the gay porn ball on ball either guys

but yeah drop off should occur on every shot not just one out of 10 if that were the case

i give you two...lol

the second one is very clear