[DonVoigt]

GT,
just fyi, the piloted drill mentioned by calibrator is a great idea.
Only downside is $75, and 6-8 wk lead time from Pacific.

I plan to try to make a similar "piloted drill" from a stepped drill, by adding the pilot.

Calibrator wrote:
"There are some that will have a 90 degree cutting edge that would allow you to leave a square shelf as a stop at the muzzle end if you halted .060-.090" shy of breaking through."
Unfortunately the step Must be at the rear, a straight liner will not "fill" the chamber area of the luger barrel, and requires a large step
at the chamber end.

Rich,
for sure this doesn't make any sense economically, but 1900 barrels are not plentiful. GT is trying to save a matching 1900, with a bulged barrel.

We're doing this for "fun", as you have so many of your cool projects!