Wiktionary
coach gun
n. A double-barrelled shotgun with very short barrels.
Wikipedia
Coach gun
A coach gun is a double-barreled shotgun, generally with barrels approximately 18" in length placed side-by-side. The name comes from the use of such shotguns on stagecoaches by shotgun messengers in the American Wild West and during the Colonial period of Australia. They often came in 10 gauge blackpowder.
Usage examples of "coach gun".
Foley took stance with his left arm tucked into the small of his back and the coach gun leveled like a huge pistol.
His aide picked up the coach gun and wiped it clean with his bandana.
Bartin was beside him, hook ready, his double-barreled coach gun in his good hand.