Your best bet is to find a 'smith who knows how to crown using a lathe. It IS the very best way to cut a crown on a barrel. Piloted tools, in the hands of a novice, can make anything from acceptable results to trash. Done on a lathe, "dialed in" on the bore, is the proper way. You may or may not 'gain' any accuracy, depends on wheather the crown is messed up now, or not. Sounds like you're dealing with a factory barrel. Many factory crowns are not close to perfect. Crowning with piloted tools, by hand, is the less than perfect way to do the job.
