Today while shooting my BM Carbine I noticed that the trigger did not seem right. I checked and noticed that the trigger pin had moved to the right and the pin actually came off the frame on the left side and the trigger was tilted toward one direction. This had happened once before about 3 weeks ago.
I know the extension of the trigger spring is to hold this pin by applying pressure to groove on the pin but the groove on my pin is not very deep or strait (the groove is rounded). I checked this pin again tonight and compared to a Colt it only requires small amount of pressure to push it to the left.
My question is, can I order another pin with slightly larger OD so it will fit tighter? Is there another trick I should use?
I put them in 2 weeks ago and they fit a little tighter than the original pin. However, when I shot my rifle last weekend the new pin backed out again after only about 80 rounds.
Last night I was cleaning the rifle and I kept looking at the trigger assembly because something didn't look right. I kept comparing the diagram on my AR manual to the rifle's trigger group for about 10 minutes. Finally I realized the problem. The hammer spring which "holds" the trigger pin was not angled right. Actually the hammer spring was assembled in reverse so the spring would un-coil when hammer was cocked instead of coiling when cocked.
I took the rifle out today and shot 300 rounds and the pin didn't move. Works great.