Description Factory Ruger Firing Pin Stop fits ALL Mark Series Pistols ever made (including MK-IV). (**The very first 1949 – 1952 production years could differ, best to observe closely on these**) These are easy to lose when the gun is apart. They can just fall out of the bolt when it’s out of the receiver unknown to the handler. We’ve even seen guns that had these missing. Without one the firing pin will ding the chamber causing chambering and extraction issues and can destroy the chamber if left alone
