KWA Puffing Problem

[bigwavedave]

I'm having a problem with a like new KWA ATP that I've had sitting around for awhile.  It's about a year old but had never been skirmished and just used in my garage, worked fine till recently.

On magazine #1:  Issue with it puffing on the first 7 or 8 shots and then it gradually works into full cycle.  I can hold the gun vertically aiming down and it will cycle first several shots great, and as I raise it up to horizontal it will begin to puff and not reset the trigger.  Seems like as the gas in the mag cools it begins to cycle better as well.

The second magazine won't cycle at all and puffs but you have to manually reset the hammer each time to get it to even puff. vertical, horizontal no difference.

I'm wondering if the increase in ambient heat has caused the mag valves to be more finicky or if this is a hammer spring issue.  If there's a fix for this without replacing springs I'm curious what it is.

[Red Devil]

I had the same problem with some of my mags also. After you fill them with gas release some of it from the mag and try shooting it.

[Uchiha Itachi]

I had the same problem and sent mine back...then sold the new one.

Does the trigger stay back as well?

[bigwavedave]

I had the same problem and sent mine back...then sold the new one.

Does the trigger stay back as well?

Yes it's acting as if the hammer spring isn't strong enough to knock the mag valve.  Apparently this is a problem with the increase temps. in my garage from what I've read.  I just wasn't sure if it's caused by the mags or by the piston or nozzle swelling in the heat.

[Uchiha Itachi]

It's possible, but mine was brand new and came broken. Mine got so bad it went into auto and was spewing gas randomly.

I was told that the problem may have come from the trigger bar. They told me that the trigger bar may not be resetting, but the cause was unknown.  However, my KWA 226 had a similar problem due to the heat warping the plastic slightly in the lower receiver which caused the trigger spring to not set right. I had to build a new buffer to increase the tension. It would puff just like the ATP did when I had it(before the fix), except the Sig's hammer couldn't reach the release valve so auto/spewing never occurred.

I never checked the Sig's problem to the ATP. The ATPs seem to be involving a resetting situation. If you take off the slide you'll notice the giant hammer that is pushed back by the slide. The gun is designed to push that down, lock, and reset the trigger. My gun was having a failure and either not locking or resetting the trigger, as manual cocking still did work on it.

It's why I sold the gun and never bought KWA again.   

[spazz]

it sounds to me like there is to much gas pressure in the mags. it could actualy be the combo of higher tempretures and a weakening hammer spring. try filling the mags then sticking them in the fridge for a lil while till they are cool (about a half an hour) if the cycling seems to get better, i would start to look for an upgraded hammer spring.

[Uchiha Itachi]

When I had mine we did try that with the 4 magazines I had with it. Each magazine had the problem and I never left them in the heat. When we tried the extended KWA Glock mag, I ended up with an auto ATP that wouldn't stop.

[ThatGuy]

More hammar! LOL
I'm going with spazz and Chris  to much pressure and not enough hammer spring  to knock the valve.

[bigwavedave]

Well just to update.  I threw the mags and the gun in the fridge for about 5 minutes.  No more problem.  My guess is the ambient heat in my garage was causing the gas in the mags to expand enough to keep the hammer from doing it's job.  Hopefully the ambient temps arent' over 90 at LC.

[Jaredvp]

(I know this is a slightly older post, but this is a common problem for many GBB pistols and here is the cause/solution to it.)

I have the TM XDM 40 and it does the same thing in the summer when I use propane in it. I have benn talking it over with Jared (the old gear box tech) and our ending conclusion was it's a built in safety in the mags to prevent too high of pressure gas from being released into the gun and possibly causing it to break.  When switching to a lower pressure gas, in my case HFC134a, it fires perfectly. It's a temperature problem with the guns. So the solution is just use lower pressure gas in the summer and then you can return the the other gas after the temperatures drop down

[XavierMace]

TM's are only designed for 134a to begin with.  It's not a "safety" feature.  It simply wasn't designed to function with mags under that high of pressure.