The Winchester M12 shotgun is a pump-action shotgun with an external tube magazine that was used by the United States during World War II. The caliber came in either 12, 16, 20, or 28 gauge. Though 12 and 16-gauge options were not initially available to troops while the original caliber was fitted for 20 gauge. The total weight of the M12 was around 3.6 kilograms while its total length was about one hundred centimetres. Magazine capacity of the weapon was six shells that could be shot at a rate of fire of up to twelve rounds per minute.