Loading is easy and fast??
I dudnt know that. I’ve never fired a BP shotgun or watched one being loaded. In my mind, a shotgun requires more accoutrements , more steps, and more concentration. The civilian carried a powder flash and a shot bag. Im not positive but I think you have to ram a wad on too of the powder and on top of the shot. After its all done, I would worry about the load being jarred loose while being carried on horseback.
Would like to hear more of your experience with muzzleloading shotguns.
The muzzleloading shotgun is a bit different from a musket. The loading sequence for an unloaded and ready gun- charge the gun with powder (sxs are a bit different), ram over powder wad, ram shot wad (cushion), add shot, ram over shot card to hold shot in place. If the cards and wads are the right size, they'll hold up to a fair amount of handling and jostling. Even on horseback, the gun would have been carried in such a fashion as to not be unsafe, think muzzle up so for the shot to become dislodged would not be a real problem.
Fast to load? Not hardly but if loaded with large shot like #4, a shotgun is devestating at close range. A trooper with a SxS has two hard hitting shots and then he'd probably fall back on a revolver with extra cylinders or even extra revolvers. Couple that with the ability to engage and disengage at will and you have a formidable opponent.