For some reason my bolt won't go all the way back. It will go back and push into the safe position, but it will not go all the way to the second hole back where it pushes in to hold the chamber open. It goes right up to it, needs to go another 1/16" - 1/8" to push in, but won't. I've taken it apart and looked at everything, but I can't figure this out. Need help bad!