I have several outlets local that stock CCI caps in 10 and 11. What I have done is dress all my nipples to take CCI #10's. Chuck the nipple in a drill, use a slow speed, some jewelery files. Finish with fine sand paper. Like kwhi43 said, the caps stay tight with the polished surface. You are modifying the diameter, taper and length.
Treso's are great if you have just a few revolvers. I didn't want to spend 1K to outfit my collection.