Dwell won't matter if the bolt is not returning to the rear. Dwell is only a matter of how long the bolt goes forward to shoot the ball. It sounds to me like the bolt is sticking and slightly blocking the breach.
I would suggest giving your LPR and Bolt a good clean and lube. Then shoot one shot at a time without a hopper. Look into the breach and watch for movement of the bolt. Watch for the center of the bolt, that's the place where you would notice the lag. Turn your LPR up until there is no lag and your bolt returns fully to the rear and you can't see it sticking in the breach. This fix you can do at home without paint and just a little bit of air.
Then go out and shoot over a chrono to see what you got. Let me know.
EDIT: Oh yea, and make sure your On/Off is turned "ON" fully and the tank is screwed in completely.
Black 2k2 MQed Cocker