It's been many years ago, but I cut off a .22 barrel, then carefully filed and sanded it square, then lapped it with a round head brass screw in an eggbeater hand drill. It came out very nice. One tricky part is avoiding burrs at the edge of the bore. I checked with a clean q-tip that would catch fibers on any burr that was present. I've had crowns done by gunsmiths fail that test. Then there was the smith that crowned another .22 for me, and left so much burr that I couldn't get a cleaning rod through it, but that's another story.
Paul
