I've had, in the past, a Walker, 2nd Dragoon, and 3d dragoon replicas. I don't have any right at the moment, but when I had these I shot them quite a bit. As for cap size, my only comment is that in my experience with a variety of cap and ball revolvers I've found that 10 or 11 will work on any of them, Sometimes, depending on brand, the 10's will fit tighter--too tight, in fact. I found this true with the RWS caps. Remington caps sometimes fit a little loose. CCI seems to be the most consistent. I'd suggest that you buy a can of 11's first and see how they fit. If they are a little loose, then pinch them a bit before putting them on the nipple, and the next time try a tin of 10's of the same brand. Even if the 10's don't fit down all the way, you'll still be able to shoot them up. You'll have to experiment a bit and find out what's best before buying them by the thousand and using a capper.