Rifles had moved from flintlock to caps by the Texas Revolution. (The Mexicans were still using surplus British flintlocks at the time).
Civil War revolvers were quite accurate - in fact no different than modern pistols.
Will Ghormley was mentioned. If you haven't seen his stuff before, look up his web site or his postings on Leatherworker. He's done a lot of holsters for Hollywood and has posted a lot of helpful stuff for us amateurs.
Hollywood uses stuff that looks cool, but frequently doesn't match equipment to the right era. For example, there's a movie, Man from the Alamo, where everyone is shooting Colt SAAs (from 1872+) in a fight that took place in 1836. It would be like seeing jet fighters in WW1.