I'm far from an expert with mags, but I'll try to break down what's happening/when/how etc.
What I have: x valve, lvl 10 standard rt on/off (I had a ULT in there with similar symptoms) classic rail, ule body and medusa frame. 1200psi ninja reg. I have a regulr HP ninja tank but didn't test it with that. I don't know if either of them have any air left at this point anyway.
Symptoms: These have been present since I got this thing in the first place last year.
When I air up, occasionally there will be a slight leak, a tiny bit of pressure on the trigger stops the leak. (even when that pressure is removed again).
sometimes when firing repeatedly (or single shots) that slight leak returns, a tiny bit of pressure on the trigger leaks to what sounds like the bolt cycling without firing and the leak stops again.
the next time I fire it tends to fire 2 paintballs (which is what lead me to think the bolt cycled w/o firing)
When the leak is not present, some pressure on the trigger leads to a leaking sound.
So my thought is that the on off pin is too long (which would mean both the standard rt and ult pins were both too long?) as it seems that air is flowing before the sear is releasing the bolt.
It will RT/full auto without issue some/maybe more than 1/2 the time. I haven't mastered the exact trigger pressure for consistent RT. Before chronoing at my recent game I had too much fun letting my new rotor feed the beast, I almost went through a whole hopper.
At chrono speeds were inconsistent (260>140>270, etc) it was doing the double feed thing so I think that probably had a big influence on the chrono inconsistency. Previously the chrono had been pretty solid.
So far I have disassembled the valve (as far as I can by hand) checked the orings, etc. No orings looked bad and when reassembled there are no obvious leaks. It cycles as it should, but still presents with the same symptoms. (I don't have a chrono at home so I don't know if it's consistent or not)
I hope someone goes *ding* it's this.... otherwise I may have to hand it off to my local field owner/mag guru so he can exorcise the demons.