filmokentucky has it right...keep that off hand w2ell back of the front os the cylinder. Will add a bit more:
It takes a bit to get use to the percussion caps going off that close to your face...do find loads/nipples/caps that don't fragment. The happer is pretty good protection, but it's still distrubing to have a cap fragments dinking off you shooting glasses. IF you demand higher power loads, then try better replacemnt nipples and fiond a cap that will bend rather than shatter.
Keeping you hand behind the cylinder face is obvious...but even with your hand well behind, those that like to avoid the belt wad under teh ball type loading in favor of a cylinder full of grease may want to change their minds. I still use grease even though I use the felt wad, but i use a whole lot less.
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the stocked pistols aren't much differnt (just taht the noise is closer to your ear). Do belive the Rem. 1858 carbine is more accurate than the stocked revolvers, not just from better sights and increased sight radius, but froma lot betteer feel of the stock's grip....those detachables are pretty good, but still feel like you are gripping an after-thought.