Body and Valve not getting along, double firing.

[audioSLAVE]

I went to swap classic valves in this marker and after doing so I got that autoresponse effect when the gun would fire twice, once when pulling trigger and again when the trigger is released. I did not have this issue with the valve I switched out with, nor did I have any issues with the "problem valve" in its previous marker.
Bolt lip looks like it is used but not abused condition, rail bushing is present, I substituted another sear even though the one in it looked fine. I cleaned on/off o-rings even swapping out complete on/offs. I swapped out bolts. There's your standard gap between sear rod and trigger. I even put a Powerfeed body on this set up and the issue went away with the "problem valve." It seems to be the combination of the valve and the blue ULE, those are the only two constants that are giving me the issue. I tried two other valves in this gun and I did not have any issues. All valves used in testing were Level 7s, velocity of problem valve unknown. What am I overlooking? Thanks in advance.

http://img.photobucket.com/albums/v246/audioshack/EC01BD0C_zps4e697ba0.jpg (http://smg.photobucket.com/user/audioshack/media/EC01BD0C_zps4e697ba0.jpg.html)

[Cyco-Dude]

what valve did it have in it before? have you tried putting in an rt on/off and playing with different pin lengths? does it have the same issue with another, working classic valve? with the components pictured, have you tried swapping the ule body with a stainless am / mm body? with the components pictured, have you tried swapping in a different rail (and if so, what rail specifically)? is the bolt spring and sear lip in good condition? you said the bolt lip was a little worn, have you tried one that's in better shape? are there any leaks when you hold the trigger?

[OPBN]

Just some suggestions. Leave out the detent when testing. Chrono it and check the velocity. Alternatively, turn it up and down to see if it makes a difference. I've also had some that I had to fiddle with the tightness of the Field strip screw to get them right. I don't recognize the rail, but assume the body sits flush?

[audioSLAVE]

I've used only classic valves on this and swapped out components from valves that do work on this set up. Usual story of almost out of air for testing too. I'll try loosening field strip screw, removing detent, alternate rail and I think I have a new bolt I can try. I'll measure pins too, I'm curious. It is Luke's Teth rail, I was wondering about ULE pim but appears to be sitting flush. Not sure when I'll be able to chrono it but I'll mess with velocity as well if I can get more air. I'm about to start a two week work stretch as well so if you don't hear back that's why. Thanks for input. Worse case scenario would be keep a valve that works on this set up, lol, but this has me baffled and it's probably stupid simple.

[audioSLAVE]

Alright swapped out rail, another ULE body, bolt, one at a time with no real luck. Venturi bolt sort of worked but I think the outer lip was rubbing on inside of body preventing it from double firing, there was blue ano wear on it and sear was not fully returning. I tried no detent, I tried increasing velocity that did not work.

Even though I swapped classic on/offs, I rebuilt it anyway except for bottom o-ring and still no luck. I did however try two different RT on/offs with .750 pins and both of them were successful in getting rid of the double firing. The classic on/offs pins I tried were both .750 as well. So not sure exactly where this leaves me as far as isolating the issue.

Back to classic on/off. When I did pull the trigger and hold it there was no leak, however if I held it long enough it would slowly recharge and fire again without me releasing the trigger.

[athomas]

Back to classic on/off. When I did pull the trigger and hold it there was no leak, however if I held it long enough it would slowly recharge and fire again without me releasing the trigger.That indicates a leak in your on-off.

[audioSLAVE]

That indicates a leak in your on-off.

Any idea why this is double firing and the leak is more obvious with a ULE body versus when the valve is used with a stainless steel body?

[athomas]

If there is a leak on the sealing edge of the on-off oring, then it often causes a burst of air into the chamber as the the on-off opens before the sear rotates far enough to catch the bolt. If the on-off oring or combination of oring and pin are just barely making contact when the sear is barely catching the bolt using the powerfeed body, then a tiny difference in the way the ULE body sits could open the on-off up early and affect the timing. The difference between bodies is probably just a tiny difference in the fit, but it could cause your problem. Instead of swapping on-offs or cleaning the top oring, try swapping the top oring with a brand new teflon one. If you still have the issue, put in an emag quad oring. The only downside to using the quad oring is that you won't be able to run CO2.

[audioSLAVE]

If there is a leak on the sealing edge of the on-off oring, then it often causes a burst of air into the chamber as the the on-off opens before the sear rotates far enough to catch the bolt. If the on-off oring or combination of oring and pin are just barely making contact when the sear is barely catching the bolt using the powerfeed body, then a tiny difference in the way the ULE body sits could open the on-off up early and affect the timing. The difference between bodies is probably just a tiny difference in the fit, but it could cause your problem. Instead of swapping on-offs or cleaning the top oring, try swapping the top oring with a brand new teflon one. If you still have the issue, put in an emag quad oring. The only downside to using the quad oring is that you won't be able to run CO2.
I had replaced the Teflon o-ring with no luck. I think I still have a quad o-ring hanging around from my emag. I'll try that out of curiosity. Any reason why the RT on/off seems to work?

[athomas]

The Rt on-off probably has a slightly different fit compared to the classic on-off. That tiny difference is probably enough to overcome the body differences.

[audioSLAVE]

Thanks for all the input. When I try the quad O-ring I'll post results.

[audioSLAVE]

Quad O-ring solved issue as well. Good to have another option. Thanks again for everyone's input.