If you feel blast of air to your face, it's the bolt o-ring..otherwise the TP seal is upside down
I will try a little O ring on top of the transfer port. This gun was leaking there with the old plastic breech. The previous owner buggered up the plastic breech, so I had to put the steel breech on. This gun has been a thorn since I got it!! In the meantime. I broke down and bought a new 1322. Its spitting out a 22 cal pellet at 450 to 460 fps with 10 pumps. I had put walnut furniture on the 1377 and Iam transferring it over to the 1322. The black plastic just doesnt cut it. Crosman should have stayed with the imitation wood at least!!!
Well still not right. Getting only 375 to 400 fps with 10 pumps. I think I will keep it for parts. Has never worked right for me since I got it!!!!