I haven't a clue as how to tell what size this old shotgun might take. The consensus here is British, 1845-1855 or thereabouts. I'd like to have a set that fits size 11 caps if possible. The ones that are on it are not original to the gun I'd say and the No. 11 Remington's and CCI's are a super tight fit, so much so that it is actually a good bit of trouble to get them on. I actually think they may not be bottoming out on the nipple. How would I go about determining what size new ones to buy?