Greetings!
I don't know anybody who carries concealed a percussion BP revolver here.
As for doing it, Pietta makes some 1860s Colt Armys, 1851 Colt Navys and 1858 Remmies, all with short 5 1/2 barrels, and in 44 caliber. You might want to look into those. If you don't care about reloading...