caps and tightness
I have two revolvers, a Colt Open top 1860 by Pietta and a 1858 Uberti Remington. I list these because different manufacturers means slightly different nipples. I started using #10 CCI caps and never had a misfire on the Uberti, but always had half the cylinders on the Pietta not go off. I mean NO bang whatsoever. Read lots of suggestions here and thought the problem was the cap size... WRONG...
From my observation, the cap needs to be very snug since two things have to happen. First and foremost, enough sparks need to travel down through that pin hole to ignite the charge, be it BP or a pellet. On the Colt the nipples were not being pressed down hard enough for this to happen on the first strike, but usually would occur on the second hit. SECOND and very important, when the cap ignites, it needs to destroy itself in the process. If it is loose and merely squished to keep from falling off what happens is that a lot of energy slips out past the sides of the nipple, and you have a partially deformed cap that may or may not have ignited the charge. This is going to, at best , stay on the nipple, at worst it will fall into the mechanism and gum up the works. I found the latter out and it was a miserable day pulling off spent caps, re-capping and trying to clear the cylinder.
So what's the best? For my two pieces, I found that #10 CCI caps explode and splinter to such a degree that pieces of copper spit out. On pulling the hammer back the few remains drop out and do not cause any hanging problems. Firing problems on the Open Top were largely due to the cap not being pressed HARD onto the nipple. This was overcome by taking a wooden dowel about 3 inches long and then making a depression in one end with a Dremel grinding stone. The caps center in this depression and can be firmly pushed down onto the nipple. Using this dowel made every hammer strike from the Colt fire the cap, something that did not happen when I tried using my fat thumb.
I have heard that Remington caps are better than CCI's and if I can find a source for them will let everyone know what my experiences are, but for now the combination of a small dowel and #10's seems to work very well.
Hope this helps you..
KKKKFL