Short barreled shotguns predate fixed cartridges. The Confederacy was so fond of them thay had a factory in Richmond altering shotguns for the duration of the conflict.
The Burgess was the first common slide action shotgun. It had one variation that folded and had an 18" barrel, IIRC. Time frame, ca 1885.
By that time, coach guns had been guarding coaches for centuries. See old pics of blunderbusses.