There are historical examples of successful carry of muzzleloaders in conflicts. In my family we still retain the "Yankee Cannon," a model 1842 muzzle loading single shot percussion cap pistol carried by my paternal great grandfather during a little skirmish known as Shiloh in 1862. He was a lad of twenty at the time and a civilian non combatant. His Dad was a farmer and itinerant preacher, conducting services every third Sunday at Shiloh chapel. I don't know if Gread GrandDad ever fired his weapon in anger, but he survived, unlike many others in that conflict. A ML must be better than nothing...

A much better sidearm at that time would have been a six shot revolver -"shot every day of the week and reloaded on Sunday"