1916 Erfurt Breechblock face.

[sheepherder]

Originally Posted by Norme

I would remove the firing pin and grip the breech block vertically (breech face up) in a lead padded vise. Then tap down gently on the firing pin hole with a center punch. You may be able to flatten that ridge without removing any metal. Good luck, Norm

+ 1

Maybe even find a steel rod (5/16" is a loose fit) to fit inside the breechblock, and tap the ridge with a blunt ended tool...or another dowel...That way, you're not squeezing that thin walled breechblock in the vise - just the rod...

Hopefully, the 70+ year old metal has not been fatigued to the point of cracking...(think of bending a wire coat hanger back & forth...it may take the first bend...but not the second...)