Sorry for the late answer to this Saturday what is it.
It is the brreechblock from a Sauer & Sohn model 1930 pistol. This is a copy from NRA firearms assembly 2, A book you should have in your library, showing the components of the pistol. It is part number 7.
This picture shows the pistol down to it’s basic field stripping.
This shows how the breechblock fits into the slide
To assembly the pistol the slide goes over the main spring and barrel, then the breechblock is slide in from the back and the slide cap is screwed on.
A couple of views of the assembled pistol
This whole project started because I just received a second pistol but the firing pin was missing. Having a shop and a second pistol I decided to make a new firing pin. Same model pistol with only a few hundred difference in serial number range. However the firing pin from my first pistol is to large for the second pistol. In fact there a number of parts that will not interchange between the pistols. Still the firing pins turned out nice and I will change the necessary dimensions to make new ones for the second pistol.











































