1st pic here is reaming the chamber for 9mm Parabellum, with a Clymer finishing chamber reamer and floating reamer holder. I've determined that I only need to cut another .018" to get my desired headspace.

Clymer recommends high-Sulphur content cutting oil; 1/32" cut at a time; chips blown out between cuts.
2nd pic shows the reamer fully inserted; final cut.
3rd pic is barrel back on receiver w/notch cut and chamber finished. Fully assembled, almost ready to shoot...
...but the barrel still needs the feed ramp milled...
I could shoot it one shot at a time...and stick the cartridges in by hand...but I can wait...
Edit: Pics updated to show how it *should* have been done, rather than the clumsy way I did it.