If you want to know your choke, apply the money wasted(IMO) on a muzzle measuring gimmick and get one that measures the bore ID. Without knowing that, the muzzle ID is mostly meaningless. The ones made by Skeets and available from Brownells, are the most reasonably priced. I have owned and use the set for several years. One head for 10, 12 and 16, another head for 20 and 28(no .410) $181 for the set or $90 for each. Less if you get their trade discount. The brass key-ring gimmick costs about $40 and tells you very little.
