I have been having problems with primers piercing in my scar 16 lately and decided to get out my firing pin protrusion gauge. When it failed on both sides of the gauge (.028" and .036") I decided to check it out with a digital calier depth gauge and found the firing pin was protruding .044"! Well there's the problem. I put it in a drill and filed and stoned it down to .033" and will have to test it at the range. A brand new AR15 bold and firing pin I have check out at .030"

I figure I have some 7000-8000 rounds through it now as well as a bunch of dry firing. I think the tapered shape on the flange that bottoms out on the bolt is the culprit where repeated impact forced the firing pin to actually stretch.

In ARs firing pin stretch is a phenomenon I have only seen maybe three or four times in over a decade of gauging maybe hundreds of thousands of rifles for the Army as a small arms repairer. The shape of the firing pin flange and rear of the bolt are essentially flat which is probably the reason for the lack of this issue in AR type rifles.

I am wondering if any of you have experienced this in your guns.