The trick is to seal the rear of the bolt against the pin. Not sure how exactly, but I'm thinking to undercut the rear of the bolt, then glue the hard plastic stock bumper on there to hold the oring in place. If someone had access to better tools they could actually add the oring groove. Basically you want that HP air to temporarily dump into the bolt return solenoid path. I'd expect a fairly large increase in efficiency. The arrow is poorly drawn, but after sealing the bolt to the pin, all that's needed are a couple of small holes in the bolt to allow HP air to temporarily dump in the solenoid air path.