Semi, I will say that's sure different than any way I have done it. i just cut them off and use an expanding rod square I made myself to square it to the inside of the bore with a file. The old German gunsmith that worked for me told me the important thing was that it end up square to the bore not to worry about the out side, we also used a one inch ball cutter by hand to put the chamfer on.
But I will say you did a lot of work and a nice looking job.