Pete, I did a few barrels with that method. It takes a while, but I figured in the end it was faster than making a tool for the job. I put marks on the stem of the tool indicating the limits of travel in, out and center of the hone. Staying mostly in the center and drifting fore and aft, for a fairly smooth transition. It worked great and really tightened up the patterns with no noticeable affect on shooting round balls.
Robby