Pistol primers and breech block damage?

[Don McDowell]

I think most of my rifles have a primer impression on the block/bolt face, whether or not they have ever had a pistol primer fired in them or not.
I have a friend that has a modern day Freund conversion, it uses the original style one piece firing pin with the huge diameter for the Berdan size primers. He has to every time after firing, cock the hammer and drop it on the fired case before opening the action and extracting the case. If he doesn't do that after about 50 rounds the firing pin hole will get so full of brass shavings from the primer it starts giving erratic ignition like a broken firing pin.