[DonVoigt]

Rick,
you are overthinking the ramp, IMO.

Just take an original barrel and duplicate the ramp; by eye is "close enough".
If you look at many luger pistols, you will see that the ramps vary a bit, maybe even a lot.

The original drawings are available and show the design specs. They were likely done on/ with a milling machine and fixture and special cutter.

I made a fixture for cutting the extractor groove, but "cut" the ramp by hand.
I use a grinding stone, then a sanding cylinder, and polish with an abrasive tip. This serves me quite well.