More work on the 1917 Mauser trench carbine

In this post I am going to chat about a single part. The Lock frame stop. This individual part is common only to the carbine. The take down lever. you can see it here in this photo that I found on line.

This is the part in question.

Here are the patent drawings that I have been able to locate.

This last one is a color picture from a book

All the references are different then the patent drawings and while I have made a solid model of the part I am not sure it is correct.

This is the solid model.

I am currently at a loss in the proper design. I am not sure what holds it in place and it’s relationship to the magazine release. I am hoping that when I 3D print the lower receiver I can get a better understanding of how this part is actually design and fits into the weapon