There is another possible cause for this. What was the air temperature the day you were shooting?

When shooting quantities of high performance rounds or load using certain powders when the air temperature it high it is not uncommon for pressure to increase and primers to pierce.

My 22-250 best load is with H380. Fire more the 10 or 15 round in temperatures above 85F and bolt lift gets hard, primers pierce, and heads start extruding. Ruined a North Texas prairie dog hunt one time because of it.

Something to consider.