L3n4rd,
What I mean is a firing pin that is part of the hammer.They are usually larger than modern ones,and since they swing in an arc,the hole in the breech face has to be larger also.They do extend past the face in firing, but rebound with the hammer.This leaves the primer unsupported somewhat,and may be the cause of the hole in the primer.I'm pretty sure S&B ammo will show less pressure than Hornady.Of course I'm guessing with all this, since I don't have the rifle "in hand".
Mike