Leaking out the back

[Cthagreekgod]

Hello all, a quick question. I looked at the owners manual for the trroubleshooting section and it basically said it could be one of 2 things. The regulator seat, which in this case is brand new, or the Regulator Piston assembly...

But my problem is not that the back leaks all the time. Only whe I adjust the velocity to a certain point. So would that be the piston assembly or something else?

[BajaBoy]

if your shooting to hard yes its gunna leak but if your in 280's - lower then u need a new piston

[Cthagreekgod]

Thanks for the help!