Daryl
The primers are not piercing at all. What happens is you fire a round or 2 and suddenly one will feel like it has more boot than normal. Inverably when you open the bolt and eject the cartridge the primer will have fallen out either in your hand or into the magazine. Once the primer actual fell between the end of the follower and the magazine box jamming the follower.

The cases from the Factory rounds that it happens to are useless now as the primer pocket has enlarged so much that a new primer will just fall out by its own weight.

I do not and have not had any of these problems with my handloads. ( 340gr Woodleighs at 2570fps using 82grs of AR2208 powder with a crimped projectile.)

I have inspected the bolt and there is no sign of wear on the pin or the bolt face.