I'm no help regarding those specific primers Doug, but long ago Tom Armbrust tried to ballistic test vintage shells from the 30s. The results were inconsistent. Some had higher pressures, he felt related to hardening of the paper cases and wads, and some 'bloopers', he felt related to degradation of the primers (not the powder).
So if you load shells using them, I would definitely check the barrels after each shot.
These Herter's Perfect Primers were from 1967. Your box is likely later.
