leaking out the backside

[DaveA]

I've got a worrisome leak coming out the back of my Xvalve. It's obviously overpressurizing, but I've replaced all the internal seals and it helped a little maybe, but it's still overpressurzing. ANyone have any ideas or tricks to try before I send it in to AGD?
The only thing I didn't do was over lube the piston, but it has lube, and as I said all the orings and the donut and the reg pin and springs have been replaced. Thanks!~

[deadeye9]

Replace the Regulator Piston, not just its O-ring.

[rb211]

Have you chrono'd the gun? How fast are you shooting? If it is venting below 300, replace the piston as mentioned above if you have already replaced the o-ring on it.