... amen! This comes up over and over on this forum.
#1) These guns come from Italy.
#2) They could care less how our caps fit the nipples they put on them. (Some BP gunsmiths even say the cap size is metric).
#3) Caps here in the US vary GREATLY even from one tin to another.
#4) Get the Treso's as Hawg suggested.
#5) While you're at it, get them for ALL your BP six-shooters (so everything is the same).
#6) I never "pinch" a cap because it doesn't fit properly. I'm too picky I guess. I enjoy having everything as "perfect" as possible.
#7)The biggest advantage of all... The Treso's have a small flash hole. They "funnel" the flash from the cap into the powder. This focuses all the ignition out the end of the barrel with minimal blow-back and the spent cap will somewhat hold together keeping the cylinder from jamming when you cock the hammer the next time.
#8) I've heard tell in this forum, of nipples that were so worn out from YEARS of shooting, the hammer would cock itself after a round was fired as the flash-hole was horribly over-sized. There was blow-back to the extent it actually would re-cock the hammer! Seriously? Rip those nipples out and throw them away!
#9) Do these things as if your very life depended upon it. At some point it might... I hope not.
OK men, it's your turn to jump in on something I might have forgotten!