For the majority of the Vietnam war, the principal weapon of the door gunner was a medium machine gun (MG), initially, a M1919A4 .30 caliber MG, and soon thereafter, the M60 7.62mm MG became the standard helicopter door armament system. Initially however not all helicopters were armed or outfitted with a dedicated MG for door armament. For example the very first U.S. Army helicopter units, flying CH-21 helicopters, that began flying combat missions in Vietnam in 1962 didn't. Therefore door gunners on Vietnam photographs are sometimes seen using an M1 Carbine, an M14 rifle, or an M16 rifle, as their only weapon.
Initially, the door gunner's MG weapons were mounted on swiveling mounts (on a pintle mount) in order to retain and steady the door armament weapon. As the war progressed, using bungee cords to suspend/retain the MG became a common practice, as the newfound maneuverability of these "bungeed" weapons allowed for increased firing angles. However some door gunners simply continued to hand-wield the weapon for a maximum level of maneuverability of fire. This practice was commonly termed as using a Free 60.