Pretty much.
They're the two leading manufacturers for cap and ball revolvers you can purchase in the states, aside from the Ruger Old Army.
I've heard that a German firm makes cap and ball revolvers, but I"m unsure if it's still in business. Or ever was. Just one of those things I kept hearing, but couldn't verify.
Palmetto is, I believe, out of business. Its quality was -- to be kind -- less than desirable.
In the 1960s there were plenty of cap and ball revolver makers in Spain and Belgium too, but their production of such revolvers ceased in the 1980s and 1990s.
I wish someone would make stainless steel clones of the Colt Navies and Army. Colt offered them in the 1980s for a short while, with its second generation production. I saw a stainless steel 1851 and 1860 in a gun store in Tacoma, Washington about 1987. Wish to heck I'd bought one or both, but money was tight at the time.
Colt stopped offering its cap and ball revolvers in the late 1990s, leaving Uberti, Ruger and Pietta as the front-runners.
(Yes, I know that major parts were roughly made by Uberti, then shipped to the States for final finishing by Colt and its contractors. I know that. You don't have to mention it, I know it.)