I believe that shotguns specifically for southern service much like that short pedersoli were manufactured at Tallassee, Alabama.
I seem to recall there was on on display at the Chickamaugua battle field museum, but can not find my old picture book from their. The book had excellent photos, most fold out, of the guns on display there.
What later became the Cracker Cowboy problem, the one year enlistees in the FLorida Cavalry, were originally entirely self armed.
WHen I was a kid in the 1960's I ran into a couple of boys along the Styx river that had a muzzle loading double they claimed to have been a Confederate cavalry gun. the left barrel was cracked and a heavy copper pipe Had been brazzed inside the leftbarrel to greatly reduce the gauge like to something approaching 28. Of course any old beatup gun was a confederate relic in those days. ;-)
-kBob