I saw one once, the fore stock must have broken or something. It ended at the rear pipe, the two front pipes had been soldered to the barrel, they had thin spacers on them and you could see a couple of Dovetails that had been either filled or had or had the lug filed of. One of them was close to the muzzle, looked like the barrel had been cut back.
You could build one that looked like a Barn/Cellar/Attic/Closet/Wall find.
Tim C.