Here's the set-up. Steyr M357-A1, excellent condition. Functions 100% in every way - but one. Georgia Arms Canned Heat factory reloaded .357 SIG FMJ ammo. When fired, somewhere through a magazine, the gun will begin producing light primer strikes to the point it will not fire. Gun field stripped and the firing pin pulled. Turning the slide on the end, a small piece of primer, exactly the size of the firing pin hole, and with a strike dimple, falls out of the pin channel. It has obviously jammed the firing pin. Upon reassembly, the gun functions perfectly until......it happens again. It may be 1 round, it may be several, but it WILL happen. WTF's going on? Bad primers? The firing pin pulling the back off the primer? (never heard of THAT) I dunno. HELP! FWIW, ammo availability and prices have prevented me from trying different brands. The GA Canned Heat, if course, uses assorted headstamp shells, but the primers seem to be different brands, too, and they also seem to be not consistently seated (by eye).