I have a new drop-in .54 TC barrel that needed work because the crown was cutting patches, I tried the thumb and sand paper method but could tell I didn't have the crown cut perfectly on all sides.
Bill Raby used a similar tool in one of his videos to the one I made to crown a barrel so I thought I would expand on his idea and make one to use on my new barrel. I can chuck mine up in drill, his was strictly a hand tool.
I turned the tool on my hobby wood lathe, it has about a 60 degree cutting surface. I turned the small end to be slightly smaller than the bore and put a piece of tape around it to give it a snug but turnable fit to the bore to center the tool.
I taped sandpaper on the cutting edge, starting with 220 and finishing with 400
I tried hand cutting the crown but it went slowly so I chucked the tool up in my drill. While running I shifted the handle of the drill every few seconds to another position to keep the pressure constant. I would go from 12 to 3 to 6 to 9 and back to 12. This tool cut an amazingly even crown.
