We bought a second hand MkIV target a while ago. It was in pretty good nick... not perfect but overall fairly good. When i took down the bolt i noticed the firing pin rebound spring had lost a couple of coils of either end. I replace that with a new one about 12 months ago. I discovered the other day that the same thing has happed again.
There is a little bit of marring in the firing pin channel from where the coils have bounced around a bit and kind of made a few indentations. I am wondering if these are catching the spring when firing and causing it to snap coils off? Wondered if anyone else has had issues with Ruger Mark series pistols chewing up rebound springs??