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DavidSaunders · Veteran Member

I just did a bit of work on my Crosman 1077 the other day, just simple stuff. I put in the O-Ring in the detent that Crosman leaves out, put in a stronger detent spring, put in a pit weaker trigger spring, and polished up some of the moving parts. I also left out the hammer catch (at the top of the hammer with the butterfly spring).

My group size has dropped by about 20% with this Crosman 1077, much better. The biggest surprise is that I am getting 76 shots of equal power on a single 12g powerlet, and they are more powerful than the 50 shots I was getting before. I knew that the shot count would improve a bit from less wasted CO2, though I did not expect that much. I also know that less waste meant more power, though it seems more significant than expected.

Power comparison based on average penetration at multiple points on a pine board.

No working digital camera at the moment, sorry.

Average group size on 15 shot groups now 0.3 inches at 15 yards, rested with at least 20 seconds between shots, using weighed and sized Winchester Round Nose 9.8 grain pellets, no wind.

CENTURION · Member

Gippeto · Member

The oring on the detent is all that's needed there. Adding the heavier spring does nothing to improve sealing, and only causes extra drag when rotating the magazine....ie...increases trigger pull.

During the shot cycle, the co2 pressure pushes the detent into the magazine, and that against the barrel...effecting a seal. Some gains can usually be found by smoothing the magazine if there are burrs or ridges, and polishing the breech end of the barrel where it contacts the magazine.

Al