I'm one of them. Mounted over my fireplace is my great grandfather's Belgium HENRI PIEPER Double Barrel Shotgun from the 1880's. The antique has twisted barrels, but I heard that such old guns can catastrophically rupture after shooting. As a weapon, the most I can do with it is whack some trespasser in the head...
I am not saying you should fire the double, but you probably could. You might even be able to find a replacement hammer for the right barrel.
For the trouble... You can purchase a state of the art Keltec KS7 Pump 12 gauge bullpup for under $400, on sale.
From Sportsman's Warehouse
It’s probably be ok if you use black powder. Shot shells. Not worth the bother.