M2 machine gun

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This article is about the .50 caliber M2 machine gun. For the .30-06 M2 machine gun, see Browning Model 1919 machine gun.

The M2 machine gun, nicknamed Ma Deuce by troops, is a heavy machine gun designed just after World War I by John Browning. The M2 .50 was used extensively as a vehicle weapon and for aircraft armament by the United States during World War II and is still in use today. It was very similar in design to the smaller .30-06 Springfield and .303 British Browning Model 1919 machine gun.

1 History
2 Design
3 Combat usage
4 Variants and derivatives
5 International usage
6 In popular media
7 See also
8 References
9 External links

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History

Designed as an aircraft machine gun just after World War I, a role it filled later on, it was also selected for the ground role and adopted by the U.S. as the Model 1921. The latter served during the 1920s as an anti-aircraft and anti-armor gun. In 1932, the design was updated and adopted as the M2, though carrying out the same functions. With the addition of a thicker walled barrel for better cooling (though counter-intuitive, a thicker barrel has a larger surface area, so provides better air-cooling) it became the M2HB (for Heavy Barrel). Due to the long procedure for changing the barrel, an improved system was developed called QCB (Quick change barrel). A lightweight version, weighing 24 lb (11 kg) less — a mere 60 lb (27 kg) — was also developed.

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Design

The M2 fires the .50 BMG cartridge that was designed for this weapon, which today is also used in high-powered sniper rifles and long range target rifles due to its excellent long range accuracy and external ballistics performance. The M2 is an air-cooled, belt-fed, machine gun that fires from a closed bolt, operated on the short recoil principle. In this action, the bolt and barrel are initially locked together, and recoil upon firing. After a short distance, the bolt and barrel unlock, and the bolt continues to move rearwards relative to the barrel. This action opens the bolt, and pulls the belt of ammunition through the weapon, readying it to fire again, all at a cyclic rate of 550 rounds per minute. This is a rate of fire not generally achieved in use, as sustained fire at that rate will 'shoot out' the barrel within a few thousand rounds, necessitating replacement.

The M2 has a maximum range of almost 7 kilometers (4.2 miles), but its maximum effective range is roughly 2 kilometers (1.2 miles) when fired from a stable mount, such as a tripod or vehicle. In its ground-portable, crew-served role, the gun itself weighs in at a hefty 84 pounds (38 kg), and the assembled M3 tripod another 44 pounds (20 kg). In this configuration, the V-shaped trigger is located at the very rear of the weapon, with a "spade handle" hand-grip on either side of it and the bolt release in the center. The "spade handles" are gripped and the trigger is depressed with one or both thumbs. When the bolt release is in the up position, the weapon is in single-shot mode. The bolt release must be pressed each time the weapon is fired to close the bolt and reload the weapon. The bolt release can be locked into the down position resulting in fully-automatic firing.

Because the M2 was designed with intent in many configurations, it can be adapted to feed in rounds from the left or right side of the weapon by exchanging the belt-hold pawls, the front and rear cartridge stops and reversing the bolt slide guide. The conversion can be completed within a minute with no tools.

When firing blanks, a large blank-firing adapter (BFA) must be used, in order to keep the gas pressure high enough to allow the action cycle. It is very distinctive, with attachment to the muzzle, and three stiff wires extending back to the base. The BFA can often be seen on M2s in peacetime operations.

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Combat usage

The M2 .50 Browning machine gun is used for various roles:

A medium infantry support weapon
When doubled it is used as an anti-aircraft gun in some ships, or on the ground. In these cases a pair of one left-handed and one right-handed feeds are used. In some cases four to six guns are mounted on the turret.
Primary or secondary weapon on an armored fighting vehicle
Primary or secondary weapon on a naval patrol boat
Coaxial gun or independent mounting in some tanks
A primary armament in WWII-era U.S. aircraft, and the Korean-era U.S. F-86 Sabre
A long range sniper rifle, when attached with a scope. One well-known expert was US Marine sniper Carlos Hathcock during the Vietnam War. The success of the M2 in this role led to the development of actual sniper rifles based on the same .50 caliber round.

A water-cooled version of the larger M2 was used as an emplaced or vehicle-mounted anti-aircraft weapon on a sturdy pedestal mount.

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Variants and derivatives

Image:Twin .50 caliber machine gun.jpg

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AN/M2, M3, XM296/M296, and GAU-10/A

The M2 machine gun was heavily used as a remote fired fixed weapon, primarily in aircraft, but also in other applications. For this a variant of the M2 was developed (sometimes seen under the designation AN/M2, but it is important to note that there were .30 and .50 caliber weapons with this designation), with the ability to fire from a solenoid trigger. For aircraft mounting some were also fitted with substantially lighter barrels, permitted by the cooling effect of air in the slip-stream. The M3 was a more purpose built variant for remote firing use, that also featured a higher rate of fire. The XM296/M296 is a further development of the M2/M3 machine gun for remote firing applications, and is currently used in armament systems pertaining to the OH-58 Kiowa Warrior helicopter. The M296 differs from previous remote firing variants primarily in the lack of bolt latch allowing for single shots. The GAU-10/A (NSN or National Stock Number 1005-01-029-3428) has been identified as a member of the Browning M2 family through its inclusion in the June 2000 issue of Countermeasure (Vol 21, No 6, available online here). Countermeasure is published by the Army Ground Risk Management Team, and identifies important issues that soldiers should be aware of with regards to risk management and safety. Beyond this connection, there is no specific information on the GAU-10/A, and it is odd that the only online reference would be from a US Army publication as this is a USAF designation.

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XM213/M213, XM218, GAU-15/A, GAU-16/A, and GAU-18/A

The XM213/M213 was a modernization and adaptation of existing .50 caliber AN/M2s in inventory for use as a pintle mounted door gun on helicopters. The XM218 was also a lightweight variant developed for this use, also entering service under the USAF designation GAU-15/A. The GAU-16/A was an improved GAU-15/A with modified grip and sight assemblies for similar applications. The GAU-18/A, another variant of the M2/M3 family, is used in the USAF HH-60 Pave Hawk helicopter but the difference between it and other variants is unknown.

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GAU-21/A and M3P

Image:Ma deuce in UH-1N.JPG The FN produced M3 series is also in U.S. military service in two versions. One being a fixed remote firing version, the FN M3P, used on the Avenger Air Defense System. The U.S. Army would appear to use this designation for the weapon. The M3M flexible machine gun has been adopted by the USAF and the USN under the designation GAU-21/A for pintle applications on helicopters.

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M2E50 (or M2 E-50)

A long due upgrade program for existing infantry M2s and other M2s currently in U.S. Army service, the E50 finally provides a Quick Change Barrel (QCB) capability, as well as, adding a rail accessory mount, improved flash hider, and a manual safety. While it originally appeared that E50 was within the bounds of the normal U.S. Army designation system, it is actually a developmental project that stands for Enhanced 50 as in enhanced .50 caliber machine gun. The E50 is a conversion kit that can be applied to older weapons — newer machine guns can be produced to this standard, however.

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International usage

The M2 family has also been widely used abroad, primarily in its basic infantry configuration. Here is a quick listing of foreign designations for M2 family weapons.

Country	NATO Member	Designation	Description
Austria	No	üsMG M2	12.7 x 99 mm Browning M2HB machine gun
Denmark	Yes	M/50	12.7 x 99 mm Browning M2HB machine gun
Norway	Yes	M/50	12.7 x 99 mm Browning M2HB machine gun
Germany	Yes	MG50-1	12.7 x 99 mm Browning M2HB machine gun
Israel	No	מק"כ ("MAKACH")	12.7 x 99 mm Browning M2HB machine gun, used as infantry weapon, IFV mounted gun and as tank's coaxial gun
Japan	No	12.7mm重機関銃M2 (Licensed by Sumitomo Heavy Industries)	12.7 x 99 mm Browning M2HB machine gun, used as IFV mounted gun and as tank's coaxial gun
South Korea	No	K-6 (Licensed by Daewoo)	12.7 x 99 mm Browning M2HB machine gun
United Kingdom (British Army)	Yes	L2A1	12.7 x 99 mm Browning M2HB machine gun
United Kingdom	"	L6, L6A1	12.7 x 99 mm Browning M2 HB machine gun; ranging gun for the L7 105 mm tank gun on the Centurion tank
United Kingdom	"	L11, L11A1	12.7 x 99 mm Browning M2HB machine gun; ranging gun
United Kingdom	"	L21A1	12.7 x 99 mm Browning M2HB machine gun; ranging gun for the 120 mm tank gun on the Chieftain tank
United Kingdom	"	L111A1	12.7 x 99 mm Browning/FN M2HB QCB machine gun

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In popular media

The M2 is often present in computer and video games on standalone tripod turrets, or vehicle-mounted (such as on top of a Humvee). Some examples of games with M2s: