My uncle has a double-barrel revolver shotgun.
He basically extended it and added some redneck as fuck engineering to it.
Basically, not only does it revolve, but it has a thick as fuck guard surrounding the cylinder's front and back, locks the barrel in place when it's perfectly aligned with the barrel, and has some form of red-neck autoreloader extending down the barrel that automatically pulls the shells out and inserts another.
It empties the shells by extending a fucking prong and tilts it so it falls out, and then a fresh one slides down the prong into the empty spot.
He's fired it like, 70 god damn times with no hold ups, jams, or explosions, the one time a shell DID go off when it wasn't supposed to, the guard directed the slug into the ground in front of him.
No, I don't understand how it works or how the fuck he designed, the only thing I DO understand is that redneck engineering is scary.