Actually, many of the brass framed replicas that do represent real Confederate guns are not that easy to locate for purchase--at least I have found that to be true. Also the brass framed '51 Navies are generally sold at a much lower price, than ANY other cap-n-ball revolver PERIOD. Doesn't make it right, or historically correct, but it does allow many more people to have the chance to get into cap-n-ball shooting for less $.
It's kinda harsh to "damn someone" just for having less money to spend on a hobby. And if you start comparing metallurgy, weren't many of the 19th century originals just using cast iron/steel instead of (even) mild low carbon forged steels? "Some" (not all) brass is just as strong as some of the cast iron(s) or steel(s) that would have been proper on the originals.
But yes, historically, many of these brass-framed copies are just NOT correct and didn't exist EVER. Doesn't mean that we can't enjoy them--even at reduced loading and taking more care of them.
I think Uberti might still make a Griswold & Gunnison replica with open top brass frame and round barrel. I had a chance to buy one that was "in the white" for $65 about a year ago, it was a Navy Arms import. That pistol is one of the few that would be historically proper. The Spiller & Burr has a top strap and should be brass, but beyond those two guns, that should be about it (except for maybe the early Rem. pocket pistols had some brass frames--but they weren't typically a "Southern gun".)
Just shoot wisely with them, and you'll be Shooting Safely!
WV_Hillbilly