Double-Barrel Shotgun (Fallout: Brotherhood of Steel)

It is really powerful weapon through much of the game, especially with anyone with high Critical Chance, but it uses far too much ammunition.

Locations

 * Carbon Town Center, available from Jesse.
 * Carbon West, in a footlocker.
 * West Bridge of Los, can be bought from Hieronymous.
 * Los Holding Pens, can be purchased from Salieri.