[Larryjk]

I always put them in the lathe (through the headstock) in a 4 jaw chuck and put a spud in the muzzle so I can center the bore using a dial indicator. Then take the cutoff tool and cut about 1/8 inch off the muzzle. Look at the rifling and see if each land is okay. If it isn't cut another 1/8 inch off and check again. Once you get even lands all the way around, you can bevel the muzzle and lap the entrance to the bore. When you finish, the muzzle should be even, each land should look like the others and to check for good lapping, pull a cotton q-tip through the muzzle. It shouldn't leave any cotton threads hanging from the muzzle.
Happy crowning.