Just an FYI, in Cowboy Action Shooting under the Single Action Shooting Society a category exists for black powder shooters that not only include the sixguns and rifles but also the shotguns.
A friend of mine has consistently won SASS championships using black powder cartridges. On nearly windless days, it's funny to see the BP shooters duck and sidestep to get out of the way of their lingering smoke clouds so they can see the targets.
Another friend insists on using near full charges of black powder for his .44-40s and his 12 gauge shotgun. For the shotgun he uses brass casings. The range officer and target spotters are always in for a treat when he lets go, especially from a short barreled sixshooter as opposed to his 7.5 barreled one.
Another historical curiosity is that the .45 Colt started out using 40 grains of black powder but because of cylinder failures (the chamber walls were mighty thin in the Colts), the manufacturers backed off to around 38 or 37 grains. The .44-40 and .38-40 nominally carried 40 grains each because of slightly lighter bullets and more steel around the cartridges because of their smaller size compared to the .45 Colt. A .45 Colt usually had a 250 grain bullet in .455 caliber whereas the .44-40 though nearly as heavy had a .426 or .427 caliber bullet and of course the .38-40 was really a .40 caliber. And yes, the official names were .44 WCF and .38 WCF standing for Winchester Central Fire and originally designed for the Winchester '73.
Just a safety precaution regarding "sixshooters" of the 19the Century and current production Colt SAAs and their clones, load only five rounds and keep the hammer down on an empty chamber. Although a quarter cock "safety" does exist, it's marginal and prone to breakage and today's primers are much, much, much more sensitives compared to the ones in the 19th Century. This rule also applies to the "three screw" Ruger Blackhawks and .22s.