I've been searching on this forum and i can't find a related topic with a solution.
This topic has been brought up on this thread with one replying post with no solution: http://www.airsoftretreat.com/forums/index.php?topic=45021.0
Basically, I have the same problem. I have a KSC USP (not the system 7 version but the old) with an upgraded metal slide (prime) and when i take one shot all the gas spews out of the magazine with one trigger pull and i'm out of gas. Is the o-ring the possible culprit? If so, what can i do to fix this problem?
I don't know why this happened. I've been using this pistol with propane gas via propane adapter and this gun was hardly ever abused or fielded,just for some backyard plinking. I hope I can find the solution, thanks for reading.