Originally Posted By: Drew Hause
Tom Armbrust tried pressure testing some early 1900s shells and found the results to be inconsistent related to primer degradation and hardening of the fibre wads and cases (causing increased pressure.)

not only primer degradation, but nitro powder decomposing, it's not black powder, its nitro powder and after many years and decomposing some nitro powders could produce extremely high pressures. Do not shoot them, it's collector item only.

Geno.