A couple of years ago, my beloved wife bought me for Xmas a Crossman 1377 air pistol; variable pump kind that has been around forever. I have been shooting it in the basement range, and lately found it to be extremely stiff to pump. I checked it over, and did not think it was a linkage problem on the pump arm, so the piston was the only reasonable part left. I figured out how to disassemble it by driving out the roll pin that holds the pump arm and front sight assembly to the front of the pistol. Got the piston out, and the seal cup was cruddy with some type of rubbery powder. I cleaned off the cup and inside the cylinder with brake cleaner, and all seemed well. Then I started reassembling the gun.....
It turns out that the roll pin from the factory is so tight it has no spring at all, and is more like a piece of drill rod. The plastic sight assembly slides around, and the pressure that it takes to drive in the pin knocks the sight out of alignment. I can get the pin through the holes on one side, but when it hits the opposite side, it is hitting the hole off-center. I thought of a couple of possible fixes:
1. use a slightly smaller roll pin, or at least one that has some spring in it so it will compress.
2. Use a solid taper pin
3. Make a tapered pilot, like a clutch line-up tool, that will line things up, then be driven out of the way by the advancing roll pin.
4. Grind a slight chamfer on the factory roll pin and reinstall.
I don't want to introduce any looseness to the assembly. What would anyone recommend? Thanks.
Wayne