If its not resetting and leaking, reset the bolt with a barrel swab.
Remove the valve and check the length of the bolt spring and see if when its on the bolt its 1/4" or more longer that the bolt. It sounds like your spring is weak and not resetting the bolt properly.
Another problem could be body alignment. Look for the rail bushing as need4reebs said. Also check the front frame screw and field strip screws are hand tight only.
Possibly the barrel detent is to tight, throwing the body alignment off, remove the barrel and try a few shots.
Conserve air it might take a minute to figure this one out, lol.