Quote Originally Posted by MrScorcher
retro valved minimag with lvl 10 + zgrip

Leaking somewhat heavily (hissing) out of velocity adjuster. it will cycle even with the leak. holding the trigger down does not change the leaking. Velocity was around 285 last time it was chronoed, middle spring installed with 1.5 spacer(no shims atm).

Thank you for any help you can provide.
Does the leak go away when you reduce the velocity? Have you changed the oring on the regulator piston assembly?

Clean the valve. Clean the regulator piston assembly and change the oring. If it still leaks out the back, change the regulator seat oring. If it still leaks but the leak goes away when you reduce the velocity, you will need a new regulator piston assembly.