Pierced primers

[Double Trouble]

Occasionally, when I shoot "high pressure" ammo, I'll experience a few pierced primers. (High pressure = anything over 6500 psig)

I usually shoot 12 ga. RST Falcon UltraLites (3/4 and 7/8 ounce) from my ca. 1886 Parker hammer gun. When using this ammo, I NEVER pierce a primer. But I recently shot some of the RST Spreader loads & a few primers got pierced. Polywad Vintagers result in more than a few pierced primers.

My firing pins appear normal. (I don't see or feel any sharp edges/points).

Outside of it looking odd when I open the gun, it doesn't bother anything. (It's too weird to look down & see a blackened primer staring up at you - kinda' like a black eye !)

Anyone else have this problem ? Should I "worry" about this or just keep shooting the Ultralites ?

Thanks !