Boy you have got that right about what passed for a short barrel.
I have an original half stock (approx .45 cal.) slightly tapered barrel that is 41 3/4" inches long, and that was after several inches had been cut off at the breech. The known history of the barrel as related to me was: It was found on a ranch in ND doing yeoman service as a Spanish windlass for tightening a barb wire fence.
The breech had been driven into the earth and was severely rusted, (amazingly the rest of the barrel is in in pretty good shape, so I suspect wrought iron) the guy who found it hacksawed off the rusted portion and for some fool reason chiseled the under rib off (no sign it was ever anything but a half stock) which was held on with six screws. It was held to the half stock fore end with only one under lug, the bottom three flats under the half stock appear to have been rather crudely ground, with the rest of the barrel flats filed smooth. It had a silver blade front sight (gone, but filed smooth and shows how it was done) inletted directly into the center of top flat, the rear sight is missing
I wish I could have seen the breech to have determined if it was a flint or nipple gun.