I replaced the firing pin on my Ruger KP345 (semi 45acp) and I had trouble getting a couple of the little gizmoes back in. The gun seems to function fine without them! (ha ha ha) But, I figured I should keep playing with it, until I get them back in there. Although, they seem like they're just part of some elaborate safety system, that is probabaly overkill. Also, there's that darn spring that goes in the switch for the safety on the side of the slide. I know where it goes, but not which way it goes in. It fires primed brass fine.