firing pin

a plunger in the firing mechanism of a firearm or cannon that strikes the cartridge primer, igniting the propelling charge.

Origin of firing pin

First recorded in 1870–75

Yes, sir; it shows just a portion of the primer, and a very small portion of the firing-pin impression.

Warren Commission (3 of 26): Hearings Vol. III (of 15) |The President's Commission on the Assassination of President Kennedy
If you go through you can pick out places in the firing-pin impressions, that are similar, by yourself.

Warren Commission (3 of 26): Hearings Vol. III (of 15) |The President's Commission on the Assassination of President Kennedy
He took it from her and pointed out where it had been dented by the firing-pin.

Hidden Gold |Wilder Anthony
And what about the area of the primer around the firing-pin impression?

Warren Commission (3 of 26): Hearings Vol. III (of 15) |The President's Commission on the Assassination of President Kennedy

This is the firing-pin impression you are looking at right here.

Warren Commission (3 of 26): Hearings Vol. III (of 15) |The President's Commission on the Assassination of President Kennedy

firing pin

the part of the firing mechanism of a firearm that ignites the charge by striking the primer