Proof Firing

[Bob Seijas]

Just to dot the i, every M1 barrel was proof fired separately after completion, and the letter P was stamped on it to denote that. When it was assembled to a rifle and the rifle was proof fired, a punch mark was to be put in the loop of the P as evidence. In early production this was done carefully as shown, but as production ramped up, the original P became smaller and the punch was hurriedly stamped only in the general vicinity of it.