It's easy. If you don't have access to a lathe, go to an autoparts store and buy a tube of valve grinding compound. Go to the plumbing aisle at Home Depot and buy a kit that has the parts for connecting a toilet tank to the toilet base. In that kit there will be two large brass screws with domed heads. Chuck one of the brass screws into a variable speed electric drill and smear the domed head with valve grinding compound. Clamp your rifle barrel vertically in a vise. Press the domed screw head into the muzzle and run the drill at slow speed. Wobble the drill with a circular motion as it grinds the crown so the crown is concentric with the bore. You have to re-apply the valve grinding compound several times. You may need to use both screws as the brass wears down pretty fast. Should take about 30 minutes to achieve a decent crown. Polish with emery paper wrapped around a tapered dowel. I once won a territorial match with a rifle that I crowned this way. Loaded easily without tearing the patches.
