[DonVoigt]

Rich,
there was no picts there when I looked first.

I believe the luger barrel you show was "ramped" by running a ball end mill into the edge of the chamber/bbl.

The drawing shows a curved flat with the radius to break the sharp edge -not a circular sector cut. The end on view shows it pretty well, if you feel like adding that view.

I believe the maker of that barrel just took a short cut that looked easy and that works some of the time. Maybe peculiar to that maker, I have not seen the same type of cut on the few aftermarket barrels I've handled.