Double-barreled shotgun
Doc Holliday and his double-barreled shotgun
Bandito and his double-barreled shotgun
The double-barreled shotgun was a variant of the standard shotgun. This shotgun had two parallel barrels, allowing for the firing of two individual shots.
In 2268, a gangster affiliated with Boss Jojo Krako was armed with a double-barreled shotgun. (TOS: "A Piece of the Action")
Later that year, in a simulation of the gunfight at the OK Corral in Tombstone, Arizona, Doc Holliday was armed with a double-barreled shotgun and used it when he fired at the Clanton gang. (TOS: "Spectre of the Gun")
In 2369, in the holographic program Ancient West, Durango and a Mexican bandito were armed with this weapon. (TNG: "A Fistful of Datas")
In the holoprogram Paris 042, some of the Irish residents of Fair Haven wielded double-barreled shotguns for damaging the holodeck controls and holding Tom Paris and Harry Kim hostage. (VOY: "Spirit Folk")
In the holonovel Photons Be Free, a double-barreled shotgun was in the quarters of Captain Jenkins, aboard the USS Vortex. (VOY: "Author, Author")