This article is about the .50 caliber M2 machine gun. For the .30-06 M2 machine gun, see M1919 Browning machine gun.
The M2 Machine Gun, or Browning .50 Caliber Machine Gun is a heavy machine gun designed towards the end of World War I by
John Browning. It was nicknamed Ma Deuce by US troops or simply called "fifty-cal" in reference to its caliber. The design has had
many specific designations; the official designation for the current infantry type is Browning Machine Gun, Cal. .50, M2, HB, Flexible.
The Browning .50 machine gun has been used extensively as a vehicle weapon and for aircraft armament by the United States from
the 1920s to the present day. It was heavily used during World War II, the Korean War, the Vietnam War, as well as during operations
in Iraq in the 1990s and 2000s. It is the primary heavy machine gun of NATO countries, and has been used by many other countries.
It is still in use today. It was very similar in design to the smaller Browning Model 1919 machine gun.
3 Combat use
4 Variants and derivatives
4.1 M2 variants
4.2 AN/M2, M3, XM296/M296, and GAU-10/A
4.3 XM213/M213, XM218, GAU-15/A, GAU-16/A, and GAU-18/A
4.4 GAU-21/A and M3P
4.5 M2 E-50 (M2E50)
5 International usage
6 See also
8 External links
Using a round originally designed by Winchester, the .50 BMG round was designed as a response to the German 13mm anti-tank
rifle of World War I and employed in a redesigned and scaled-up M1917 Browning .30 cal. machine gun. It was quickly adapted
to the anti-aircraft role. 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 fulfilling the same
role. As with the M1921, the original infantry variant of the M2 was equipped with a water jacket for cooling . A variant without
a water jacket, but with a thicker-walled, air-cooled barrel superseded it (air-cooled barrels had already been used on variants for
use on aircraft, but these quickly overheated in ground use). The added mass and surface area of the new barrel compensated,
somewhat, for the loss of water-cooling, while reducing bulk and weight (the M2 weighed 121 lbs, with water, whereas the M2 HB
weighs 84 lbs). This new variant was the designated the M2 HB (HB 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.
The M2 is a scaled-up version of John Browning's M1917 .30 caliber machine gun (even using the same timing gauges), and fires
the .50 BMG cartridge, which today is also used in high-powered sniper rifles and long range target rifles due to its excellent long
range accuracy, external ballistics performance, incredible stopping power, and lethality. 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
450–550 rounds per minute (600–1,200 M2/M3 in WW2 aircraft, 300 synchronized M2). 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
machine gun's sustained rate of fire is considered to be anything less than 40 rounds per minute.
The M2 has a maximum range of 7.4 kilometers (4.55 miles) when using the M2 ball ammunition, with a maximum effective range of
1.8 kilometers (1.2 miles) when fired from the M3 tripod. 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 "butterfly"
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 the center.
The "spade handles" are gripped and the butterfly trigger is depressed with one or both thumbs. When the bolt release is locked
down by the bolt latch release lock on the buffer tube sleeve, the gun functions in fully automatic mode. Conversely, the bolt release
can be unlocked into the up position resulting in single-shot firing (the gunner must press the bolt latch release to send the bolt
forward). In either mode the gun is fired by pressing the butterfly triggers. Recently new rear buffer assemblies have used squeeze
triggers mounted to the hand grips doing away with the butterfly triggers.
Because the M2 was intentionally designed to be fit into many configurations, it can be adapted to feed from the left or right side of
the weapon by exchanging the belt-holding pawls, the belt feed pawl, the front and rear cartridge stops, and reversing the bolt switch.
The conversion can be completed in under a minute with no tools.
When firing blanks, a large blank-firing adapter (BFA) must be used to keep the gas pressure high enough to allow the action to
cycle. The adapter is very distinctive, attaching to the muzzle with three rods extending back to the base. The BFA can often be seen
on M2s during peacetime operations.
 Combat use
An M2 fired from a rigid-hulled inflatable boat.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, one M2 with a left-handed feed and
one with right-handed feed are paired. Four and six guns are also sometimes mounted on the same turret.
Primary or secondary weapon on an armored fighting vehicle.
Primary or secondary weapon on a naval patrol boat.
Secondary weapon for anti-boat defense on naval destroyers, frigates and aircraft carriers.
Coaxial gun or independent mounting in some tanks.
Fixed-mounted primary armament in World War II-era U.S. aircraft such as the P-47 Thunderbolt, P-51 Mustang, and the Korean-era
U.S. F-86 Sabre.
Fixed or flexible-mounted defensive armament in World War II-era bombers such as the B-17 Flying Fortress, and B-24 Liberator.
A long-range sniper rifle, when equipped with a telescopic sight. This use was discovered by US Marine sniper Carlos Hathcock
during the Vietnam War. The M2 had two traits that made this possible:
The M2HB has a full automatic mode activated by locking down the bolt release lever between the butterfly triggers. Full
automatic fire mode is achieved by rotating a snap spring on the exterior of the buffer housing to hold the bolt release down. The
M2HB can be fired dependably in single-shot mode with the bolt release up and pressing it to load each round. A skilled gunner can
can fire single rounds by quickly releasing the butterflies on full automatic mode. In either mode the gun is fired by pressing the
Its traversing-and-elevating (T & E) mechanism attached to the tripod made accurate aiming possible, by turning the traversing
handwheel and elevating handwheel until the target was in the sights.
Using the Unertl scope supplied on his Winchester Model 70 .30-06 sniper rifle and a mounting bracket of his own design, Hathcock
could quickly convert the M2 into a rifle that, in single-fire mode, could accurately hit targets at up to 2500 yards--twice the range
of the Winchester sniper rifle. The success of the M2 in this role led to the development of purpose-built sniper rifles, generally bolt-
action, designed to fire 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
Commonwealth use of the .50 was limited in the Second World War, despite it being standard armament on US-
built/designed AFVs such as the M4 Sherman or M10 Wolverine that began to see use in British, Canadian, Australian and New
Zealand units from 1942 on. Commonwealth tank crew commanders more often than not deleted the .50 altogether as being of
limited use, given three factors. First, the weapon was an anti-aircraft weapon, and Allied aerial superiority rendered it unnecessary.
Second, in order to employ the weapon against ground targets, the commander had to exit the turret and expose himself to enemy
fire. Finally, Commanders, especially in Italy, also found that the gun caught on low-hanging trees and vines and posed a danger to
the crew commander's head and face.
 Variants and derivatives
 M2 variants
The basic M2 was deployed in US service in a number of subvariants, all with separate complete designations as per the US Army
system. The basic designation as mentioned in the introduction is Browning Machine Gun, Cal. .50, M2, with others as described
The development of the M1921 water-cooled machine gun which led to the M2, meant that the initial M2s were in fact water-cooled.
These weapons were designated Browning Machine Gun, Cal. .50, M2, Water-Cooled, Flexible. There was no fixed water-cooled
Improved air-cooled heavy barrel versions came in three subtypes. The basic infantry model, Browning Machine Gun, Cal. .50, M2,
HB, Flexible, a fixed developed for use on the M6 Heavy Tank designated Browning Machine Gun, Cal. .50, M2, HB, Fixed, and a
"turret type" whereby "Flexible" M2s were modified slightly for use in tank turrets. The subvariant designation Browning Machine Gun,
Cal. .50, M2, HB, Turret was only used for manufacturing, supply, and administration identification and separation from flexible M2s.
Specific aircraft versions were also developed, and these subvariants are discussed in the following paragraph along with the
 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 official designation for this weapon was
Browning Machine Gun, Aircraft, Cal. .50, M2 followed by either "Fixed" or Flexible" depending on whether the weapon was used as a
fixed forward firing gun or for use by an airplane's crew, such as a waist gun position on a B-17.
The M3 was a more purpose built variant for remote firing use, that also featured a higher rate of fire. This weapon was used on the
XM14/SUU-12/A gun pod.
The XM296/M296 is a further development of the M2/M3 machine gun for remote firing applications, and is currently only used in an
armament system for 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.
 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 using the M59 armament subsystem.
The GAU-15/A, formerly identified as the XM218, is a lightweight member of the M2/M3 family. The GAU-16/A was an improved GAU-
15/A with modified grip and sight assemblies for similar applications. Both of these weapons were used as a part of the A/A49E-11
The GAU-18/A, is a lightweight variant of the M2/M3, and is used on the USAF's MH-53J Pavelow II and HH-60 Pave
Hawk helicopters. These weapons do not utilize the heavy barrel, and are typically set up as left-hand feed, right-hand charging
weapons. In this configuration the gun is fitted with a chute adapter attached to its left hand feed pawl bracket. Thus, the weapon can
receive ammunition through a feed chute system connected to internally-mounted ammunition cans. Originally designed to
accommodate 1,700 rounds, these cans have since been modified due to space constraints, and now hold about half that amount.
However, many aerial gunners find the chute system cumbersome, and opt to install a bracket accommodating the 100-round cans
instead (as on the model pictured to the right).
 GAU-21/A and M3P
A .50 GAU-21/A mounted in a USMC UH-1N in Iraq in 2003The 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
 M2 E-50 (M2E50)
A long overdue 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, a rail accessory mount, an improved flash hider and a manual safety.
The E50 designation initially appeared to be within the bounds of the normal U.S. Army designation system. However, it later turned
out that the term was in fact a developmental project that stands for Enhanced 50, as in enhanced .50 caliber machine gun.
Developed primarily as a conversion kit for existing weapons, it is likely that new production machine guns will be built to this
standard. In later U.S. Army briefings, this variant has been referenced as the M2E2 or M2A1.
 International usage
The M2 family has also been widely used abroad, primarily in its basic infantry configuration. A brief listing of foreign designations for
M2 family weapons follows:
Country NATO Member Designation Description
Argentina No M2HB 12.7 × 99 mm Browning M2HB machine gun
Australia No M2HB-QCB 12.7 × 99 mm Browning M2HB machine gun (also manufactured locally under license by ADI)
Austria No üsMG M2 12.7 × 99 mm Browning M2HB machine gun
Belgium Yes FN M2HB-QCB 12.7 × 99 mm Browning M2HB machine gun, used as infantry weapon, IFV mounted gun and as tank's
Brazil No Mtr .50 M2 HB "BROWNING" 12.7 × 99 mm Browning M2HB machine gun
Canada Yes M2 12.7 × 99 mm Browning M2HB machine gun
Chile No FN M2HB-QCB 12.7 × 99 mm Browning M2HB machine gun
Denmark Yes M/50 12.7 × 99 mm Browning M2HB machine gun
Germany Yes MG50-1 12.7 × 99 mm Browning M2HB machine gun
Iceland Yes vélbyssa 12.7 × 99 mm Browning M2HB machine gun
India No M2HB 12.7 × 99 mm Browning M2HB machine gun in limited quantities
Israel No מק"כ ("MAKACH") 12.7 × 99 mm Browning M2HB machine gun, used as infantry weapon, IFV mounted gun and as tank's
Ireland No Infantry Support, HMG & Air Defence.
Japan No 12.7 mm重機関銃M2 (Licensed by Sumitomo Heavy Industries) 12.7 × 99 mm Browning M2HB machine gun, used as IFV
mounted gun and as tank's coaxial gun
South Korea No K6 a clone of 12.7 × 99 mm Browning M2HB QCB machine gun (manufactured by S&T Dynamics)
Spain Yes Ametralladora Pesada M-2 HB 12.7 × 99 mm Browning M2HB machine gun
Norway Yes M/50 12.7 × 99 mm Browning M2HB machine gun
Sweden No Tksp 12,7 (Licensed by Bofors) 12.7 × 99 mm Browning M2HB machine gun
Thailand No ปืนกล 93 12.7 × 99 mm Browning M2HB machine gun
United Kingdom (British Army) Yes L2A1 12.7 × 99 mm Browning M2HB machine gun
United Kingdom Yes L6, L6A1 12.7 × 99 mm Browning M2 HB machine gun; ranging gun for the L7 105 mm tank gun on the
United Kingdom Yes L11, L11A1 12.7 × 99 mm Browning M2HB machine gun; ranging gun
United Kingdom Yes L21A1 12.7 × 99 mm Browning M2HB machine gun; ranging gun for the 120 mm tank gun on the Chieftain tank
United Kingdom Yes L111A1 12.7 × 99 mm Browning/FN M2HB QCB machine gun (built under license by Manroy)
Switzerland No Mg 64 12.7 × 99 mm Browning M2 HB machine gun
 See also
MG 131 machine gun, German rival to the M2 Browning
XM312, proposed future replacement gun for the M2HB
List of individual weapons of the U.S. Armed Forces
List of crew-served weapons of the U.S. Armed Forces
United States infantry weapons of World War II and Korea
Colt M1911/M1911A1 | M1917 revolver | Smith & Wesson "Victory" revolver
Rifles & carbines
Springfield M1903 | M1 Garand | M1 Carbine | M1941 Johnson | Browning Automatic Rifle (BAR)
Thompson ("Tommy Gun") M1928/M1/M1A1 | M3 "Grease Gun" | Reising M50/M55 | United Defense M42
Machine guns & other larger weapons
Browning M1917 | Browning M1919 | Johnson LMG | Browning M2 HMG | Bazooka | M2 flamethrower
Cartridges used during World War II and the Korean War
.45 ACP | .38 Special | .30-06 Springfield | .30 Carbine | 9 mm Luger | .50 BMG
Gresham, John D. “Weapons”. Military Heritage. December 2001. Volume 3, No. 3: 22, 24, 26, 28, 30 (John Browning’s (M2) .50-
MCWP 3-15.1: Machine Guns and Machine Gun Gunnery
 External links
Wikimedia Commons has media related to:
M2 (machine gun)Aircraft Gunnery_.50 cal.
M2 .50 Caliber Machine Gun at Federation of American Scientists
Browning M2HB & M2HQCB (USA)
M2 .50 cal. Machine Gun at Olive-Drab.com
Quad-50 M2 .50 cal. Machine Gun at Olive-Drab.com
Video of a CG M2 showing the inner workings as it goes through the firing cycle.
|The M2 50. Caliber Machine Gun
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