Only time I ever saw this was with a particular batch of Remington 9 1/2's in a .270. Two primers from one box had pin prick leaks right at the outer circumference and gouged divots in a very nice LH Model 70 bolt face.
If nothing else it gave me a new respect for the power of a directed stream of very hot gas under very high pressure.
BTW, I threw away that batch of primers.
Gunnery, gunnery, gunnery.
Hit the target, all else is twaddle!
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