Go to the crosman forum, and search 392..lots of easy tuneups for that gunMay 8 2013 at 12:41 AM
|scot laughlin (Login classicalgas)|
Response to What velocity from a 392 should I expect?
It's likely that you got a gun where the pump head to valve body clearance got big, due to tolerance stacking in the various parts,and increased head space to the point you are losing significant pump pressure.
Does the pump arm want to spring pretty far, or almost all the way open after about the sixth pump, once you've popped it loose from the tube? There are a couple fixes for this,it's a strong indication of excessive head space.
Is the take down socket bolt(which also holds the valve in place) loose enough to allow the valve to move in the tube? Do you lube the pump head and pivots regularly?
A happy 392 with snug head space will drive a 14.3 pellet at very close to 600 fps on eight pumps..some a little more, generally not less.