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The M2 Machine Gun
The 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. It is effective against infantry,
unarmored or lightly-armored vehicles and boats, light fortifications, and low-flying aircraft.
The Browning .50 caliber
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, with only a few modern improvements. The M2 has been
in use longer than any other small arm in U.S. inventory. It was very similar in design to the smaller Browning
Model 1919 machine gun.
History
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jacket, but with a thicker-walled, air-cooled barrel superseded it (air-cooled barrels had already been used on variants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). This new variant was then designated the M2 HB ("HB"
for "Heavy Barrel"). 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 convert|121|lb|abbr=on, with water, whereas the
M2 HB weighs 84 lb). 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
Design details
The M2 is a scaled-up
version of John Browning's M1917 .30 caliber machine gun (even using the same timing gauges), 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 450–600 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), 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. Otherwise, the M2 is a single-shot weapon. Unlike
virtually all other modern machine guns, it has no safety. 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, and the front and rear cartridge stops, then reversing the bolt switch. The conversion
can be completed in under a minute with no tools.
There are several different
types of ammunition used in the M2HB, including the current types: M33 Ball (706.7 grain) for personnel and light material
targets, M17 tracer, M8 API (622.5 grain), M20 API-T (619 grain), and M962 SLAP-T. The latter ammunition along with the M903
SLAP (Saboted Light Armor Penetrator) round can penetrate up to 3/4 inch armor at 1500 meters. This is achieved by using a
.30 inch diameter tungsten penetrator. The SLAP-T adds a tracer charge to the base of the ammunition. This ammunition was
type classified in 1993.
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
The M2 .50 Browning machine
gun has been used for various roles:
* A medium infantry support weapon
* As an anti-aircraft gun in some ships,
or on the ground. The original water-cooled version of the M2 was used as an emplaced or vehicle-mounted anti-aircraft weapon
on a sturdy pedestal mount. In some cases multiple air and water-cooled weapons were grouped. In some of these instances the
mount featured 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 large naval vessels (corvettes, frigates, destroyers,
cruisers, etc).
* 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 A-26 Invader, B-17 Flying Fortress,
and B-24 Liberator.
United States
At the outbreak of the
Second World War the United States had versions of the M2 in service primarily as fixed aircraft guns and as anti-aircraft
weapons (mounted on and off a wide variety of vehicles and ships). It was also technically still in service as an anti-tank
weapon, as originally intended. On most of the vehicles the weapon was mounted on it was placed in a position designed for
anti-aircraft rather than any other use. Units in the field often modified the mountings on their vehicles, especially tanks
and tank destroyers, to be more useful in the anti-personnel role. Reports vary on its effectiveness in this role. There are
instances of reports about the "essential" nature of the weapon for anti-personnel uses.
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 below.
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 version.
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.
A number of additional
subvariants were developed after the end of the Second World War. The Caliber .50 Machine Gun, Browning, M2, Heavy Barrel,
M48 Turret Type was developed for the commander's cupola on the M48 Patton tank, and then later used in the commander's
position on the M1 Abrams tanks. Three subvariants were also developed for used by the US Navy on a variety of ships
and watercraft. These included the Caliber .50 Machine Gun, Browning, M2, Heavy Barrel, Soft Mount (Navy) and the Caliber
.50 Machine Gun, Browning, M2, Heavy Barrel, Fixed Type (Navy). The fixed types fire from a solenoid trigger and
come in left or right hand feed variants for use on the Mk 56 Mod 0 dual mount and other mounts.
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.
M2HB machine gun
Name - Browning Machine
Gun, Cal. .50, M2, HB
Type - Heavy machine gun
Origin - United States
Era - Post-WW1
Platform
- Tripod, vehicle
Target - Personnel, light-armored vehicles, aircraft
Design date - 1918
Production
date - 1933–present (M2HB)
Service - 1921
M2HB from 1933–present
Wars - World War II, Korean War, Vietnam War, Cambodian Civil
War, Falklands War, Desert Storm, Somali Civil War, Iraqi Freedom,
Operation Enduring Freedom, South African Border War
Specification
weight - 38 kg (84 lb), 58 kg (128 lb) with tripod
and T&E
length - 1650 mm (65 in)
part length - 1143 mm (45 in)
cartridge - .50
BMG
action - Short recoil-operated
rate - 450–600 rounds/min (M2HB)
750–850
rounds/min (M2 aircraft gun)
velocity - 2,910 feet per second (M33 Ball) (887.1 m/s)
Max range (updated
USMC standard) - 6767 meters / 7400 yards; Max Effective Range - 1830 m (area target), 1500 m (point target) & 700 m (grazing
fire)
feed - Belt-fed
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The Hispano-Suiza HS.404 was an autocannon widely
used as both an aircraft and land weapon in the 20th century by British, American, French and numerous other military services.
Firing a 20 mm diameter projectile, it delivered a useful load of explosive from a relatively light weapon. This made it an
ideal aircraft weapon, replacing the multiple 7.62 mm (.30 caliber) machine guns commonly used in military aircraft in the
1930s.
The HS.404 was based on the earlier Swiss Oerlikon FF S
weapons, which Hispano-Suiza manufactured under license in France as HS.7 and HS.9. In the late 1930s engineer Marc Birkigt
designed a new and much improved version with a revised action, much faster rate of fire, and somewhat higher muzzle velocity.
The result was the Type 404, or HS.404, which was widely considered the best aircraft cannon of its kind. The
404 was widely used on pre-war French designs, notably in installations firing through the drive shaft of the Hispano-Suiza
12Y engine, a system known as a moteur-canon. The HS.404 was fed by drum magazines that could accommodate at most 60 rounds.
Since in most installations the magazine could not be switched during flight, the small ammunition capacity was problematic.
In 1940, Hispano-Suiza was developing a belt-feeding system, as well as derivatives of the HS.404 in heavier calibres such
as 23 mm, but all these projects were halted with the German occupation of France.
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Type: single-barrel automatic cannon
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Caliber: 20 mm × 110 (0.79 in)
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Operation: gas operated
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Length without muzzle brake: 2.32 m
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Length with muzzle brake: 2.52 m
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Weight without drum magazine: 43 kg
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Weight (complete): 68.7 kg
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Rate of fire: 600–700 rpm
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Muzzle velocity: 840 to 880 m/s (2,750 to
2,900 ft/s)
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Recoil force: 400 kg with muzzle brake
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Amunition: Ball, Incendiary, HE (High-Explosive)
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Projectile weight: 130 g HE and HEI 168 g
AP-T
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HE and HEI rounds explosive filler: 6 - 11
g
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The "Tiny Tim" 11.75in Rocket
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In early 1944, the U.S. Navy was in need of a powerful
anti-ship weapon with some stand-off range to keep the attacking aircraft outside the range of heavy air defenses. The new
fast fighter-bombers of that time couldn't drop torpedoes, and the existing rockets were not large enough to be useful against
heavy shipping. In March, CalTech showed that a large caliber air-launched rocket was feasible, and the Navy subsequently
ordered to develop such a weapon with the highest priority. The result was a rocket of 11.75 inches diameter, which eventually
gained the nickname Tiny Tim (obviously an ironic pun on its size). The apparently odd dimension was chosen, because it matched
the diameter of the standard 500 lb SAP (Semi-Armor Piercing) bomb, which was used as the warhead, as well as the diameter
of standard oil well steel tubing, which was used as the casing.
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MK13 Aerial torpedo
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The US Mk. 13 aerial torpedo was basically a 21" (actually
22.4") type torpedo rather than the 18" lightweight used by most
other navies. It was lighter than the Mk 14 submarine torpedo and the even heavier Mk 15 surface ship torpedo, with a shorter range and smaller warhead, but was generally similar to the other
US 21" torpedoes and shared some mechanisms and designs -
and problems.
US torpedo problems were threefold: 1) they ran 6 - 10+
feet deeper than set 2) the magnetic exploder mechanism didn't work
as has been written up in many accounts and 3) the contact exploder would generally fail if it hit perpendicular to the target or other than at a narrow angle. Each of these problems took time
to recognize and sort out from the rest.
Since the Mk13 aerial torpedo shared mechanisms and exploders
with the other 21" torpedoes, the same problems would have
been present. Added to which are the additional problems that came from the stress of aerial drops, potential tumbling gyros,etc.
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