The Browning M1919 is a .30 caliber light machine gun family widely used during the 20th century. It was used as a light infantry, coaxial, mounted, aircraft, and anti-aircraft machine gun by the U.S. and many other countries, especially during World War II, the Korean War, and the Vietnam War. Although it began to be superseded by newer designs in the later half of the century (such as by the M60 machine gun), it remained in use in many NATO countries and elsewhere for much longer.
Many M1919s were rechambered for the new 7.62 × 51 mm NATO round and served into the 1990s, as well as up to the present day in some countries. The United States Navy also converted many to 7.62 mm NATO, and designated them Mk 21 Mod 0; they were commonly used on river craft in the 1960s and 1970s in Vietnam.
The M1919 was an air-cooled development of the standard U.S. machine gun of World War I, the Browning M1917, as designed by John M. Browning. The weapon originally fired the .30-06 M1 or M2 rifle cartridge from woven cloth or metallic link belts feeding from left to right.
With assistance from firearms engineers at Fabrique Nationale de Herstal, Belgium, the Model 1919 was completely re-engineered into the .30 caliber M2 AN (Army-Navy) aircraft machine gun. The .30 in M2 AN Browning was widely adopted as both a fixed (offensive) and flexible (defensive) weapon on aircraft. Aircraft machine guns required light weight, firepower, and reliability, and achieving all three goals proved a difficult challenge. The receiver walls and operating components of the M2 were made thinner and lighter, and with air cooling provided by the speed of the aircraft, designers were able to reduce the barrel’s weight and profile. As a result, the M2 weighed two-thirds that of the 1919A4, and the lightened mechanism gave it a rate of fire approaching 1,200 rpm (some variants could achieve 1,500 rpm), a necessity for engaging fast-moving aircraft. The M2′s feed mechanism had to lift its own loaded belt out of the ammunition box and feed it into the gun, equivalent to a weight of 11 lb (5 kg). In Ordnance circles, the .30 M2 AN Browning had the reputation of being the most difficult-to-repair weapon in the entire US small arms inventory.The M2 also appeared in a twin-mount version which paired two M2 guns with opposing feed chutes in one unit for operation by a single gunner, with a combined rate of fire of 2,400 rpm. All of the various M2 models saw service in the early stages of World War II, but were phased out beginning in 1943, as hand-trained defensive machine guns became obsolete for air warfare (the .50 in/12.7 mm M2 Browning and 20 mm automatic cannon had replaced the .30 in as offensive air armament as well). The .30 in M2 aircraft gun was widely distributed to other US allies during and after World War II, and in British and Commonwealth service saw limited use as a vehicle-mounted anti-aircraft or anti-personnel machine gun.
Variants and derivatives
In total there were six variants of the basic M1919 machine gun. The original M1919 featured a relatively heavy barrel, attempting to match the sustained fire capability of contemporary water-cooled machine guns. The M1919A1 featured a lighter barrel and a bipod. The M1919A2 was another lightweight development specifically for mounted cavalry units, utilizing a shorter barrel and special tripod (though it could be fitted to either the M1917 or M2 tripods). This weapon was designed to allow greater mobility to cavalry units over the existing M1917 machine gun. The M1919A2 was used for a short period between World War I and World War II after the cavalry had converted from horses to wheeled and tracked vehicles. An improved version of the M1919A2, the M1919A3, was also developed.However, by and large the most common variant of the series was the M1919A4. The M1919A4 was used in both fixed and flexible mounts, by infantry and on vehicles. It was also widely exported after World War II and continues to be used in small numbers around the world. Two variants were developed specifically for vehicular use, the M1919A5, with an extended charging handle, and the M1919A4E1, a subvariant of the M1919A4 refitted with an extended charging handle.The M1919A6 was an attempt to provide US forces with a more portable light machine gun, similar to the German MG34 and MG42 machine guns they were facing. The M1919A6 had a metal buttstock assembly that clamped to the backplate of the gun, and a front barrel bearing that incorporated both a muzzle booster and a bipod similar to that used on the M1918 Browning Automatic Rifle (BAR). A lighter barrel than that of the M1919A4 was fitted. The M1919A6 was a heavy (32 pounds) and awkward weapon in comparison with the MG34 and MG42 and was eventually replaced by the M60 machine gun.
AN/M2A specific aircraft version of the Model 1919A4 was manufactured by Browning as the AN/M2 with a thinner barrel and thinner receiver walls. It was used on US aircraft early in the war, but was replaced by the larger .50 in (12.7 mm) M2 machine gun and relegated to training duties. A derivative of this weapon was built by Colt as the MG40. This weapon is not to be confused with the Browning Machine Gun, Cal. .50, M2, Aircraft, and its full designation is Browning Machine Gun, Cal. .30, M2, Aircraft. The .30 in M2 Browning is sometimes referred to as AN/M2.