Here is a photo of my 50 cal. coning tool.
when used I just tape a piece of emery cloth onto the shaft just below the cone and wrap it around the cone counter clockwise. You only need a piece about two inches long. I put a little oil on the pilot shaft and then insert it in the barrel. Then turn the coning tool with an electric drill. It doesn't take much to do the job. you may have to use a couple pieces of Emory to complete the job. Don't go overboard. Keep the barrel where the pilot runs as clean as possible so as not to let emery dust get down in the bore and hurt the bore. You can make one of these out of hardwood and it will work for a few times but never make one out of aluminum. Aluminum will mess up the bore.
when used I just tape a piece of emery cloth onto the shaft just below the cone and wrap it around the cone counter clockwise. You only need a piece about two inches long. I put a little oil on the pilot shaft and then insert it in the barrel. Then turn the coning tool with an electric drill. It doesn't take much to do the job. you may have to use a couple pieces of Emory to complete the job. Don't go overboard. Keep the barrel where the pilot runs as clean as possible so as not to let emery dust get down in the bore and hurt the bore. You can make one of these out of hardwood and it will work for a few times but never make one out of aluminum. Aluminum will mess up the bore.