I use a hack saw, square it all up checking by eye at arm's length, polish with emery cloth backed by a file, and crown with valve grinding compound and oil on a large round head brass screw on a small electric hand drill.
Be sure to stuff the barrel with some paper towel or kleenex at the cutoff point to keep the bore clean for the entire process.
Ted
What he said. I've only done two Mausers this way, but both shot very well indeed after the process. Just take your time and be careful. I did use a square to help with the filing. Since the barrel is tapered, you have to use a little Kentucky windage, but working toward getting the same 'gap' as you move the square around the barrel was easier to me than holding the barrel at arm's length to check.
