Use the correct size o-ring for the top hat. The bolt stem is tapered, and when the bolt moves forward the stem passes through that o-ring and seal breaks which allows air to flow through the bolt to the ball. If that o-ring is an incorrect size, is damaged or the chamber pressure is too high it will blow off and cause a big barrel leak.
A frame leak could be from the bolt sail, the rear external can o-ring, the external tophat o-ring, the front mount on/off or one of the LPR o-rings, in addition to the solenoid gasket, solenoid spool or air channel plugs. If you can't pinpoint the leak, I would check them pretty much in the order I just listed them as that is it follows the most likely causes/simplest order to troubleshoot.
Edit: Those o-rings also do not need to be urethane, the original ones were but it doesn't matter in this case.
Last edited by speedy2k4 : 01-25-2013 at 08:20 PM.