1916 Erfurt Breechblock face.

[lfid]

AZjoe,

is the center small circle around the firing pin hole indented toward the rear of the breechblock ?

or is the circle protruded toward the barrel ?

if indented it would seem to match the primer diameter push against the breechblock face

if protruded it would seem to match the firing pin push against the backside of the breechblock face

good luck
Bill