John, when you set up the barrel in the lathe indicate it off of the bore and not the OD of the barrel. Slip a snug fitting pin (preferably ground) a couple of inches into the muzzle with a bit sticking out to dial it into your 4-jaw chuck. When you are done cutting the new crown, lap the muzzle with a brass 45° "center" and some fine abrasive compound. A brass wood screw with a round head could be substituted for the 45° center/lap. Chuck it in a hand drill, apply the compound, and do small figure 8's on the muzzle while slowing running the drill.
Dave is correct. The ends of the rifling (lands) need to be smooth, even and concentric with the bore. If you are working on a "rounded" style of crown, this is the typical type of grind used on the lathe bit.
![[Image: 625189.jpg]](http://media.midwayusa.com/productimages/880x660/Primary/625/625189.jpg)
Dave is correct. The ends of the rifling (lands) need to be smooth, even and concentric with the bore. If you are working on a "rounded" style of crown, this is the typical type of grind used on the lathe bit.
Willie