Nice work.
Years ago I could have bought a very rusty example of a Plains Indian cut down musket with copper tack decorations for only $60 USD.
It was in a barrel with a number of old rusty rifles of various types. It may have been used as a motion picture prop but apparently was an original Native American gun. You can't really fake that kind of wear and tear.
May have gone through Bannermans at some point.
It was carbine size and its barrel was worn to an oversized smoothbore and caked with old black powder fouling.
Looked like the only lube it ever got had been animal fat. The lock still worked and the very worn nipple was clear of debris, no doubt it could have been fired with a light load and proper sized un patched ball.
The horseback reloading method was to guesstimate a powder charge from a flask then spit an undersized ball carried in the rider's mouth down the muzzle, which the very short barrel made easy enough. Don't know how they handled the cap, with flintlock versions an oversized touch hole let powder from the chamber fill the pan.
They carried the gun muzzle high till ready to fire so the loose fitting ball didn't roll out.
The Sling swivel, which carbines of the day never had, still had a very bedraggled feather hanging from it mounted in a decorative winding of some sort.