.50 BMG

The .50 BMG (.50 Browning Machine Gun), also known as 12.7×99mm NATO, and designated as the 50 Browning by the C.I.P.,

History

In response to the need for new anti-aircraft weaponry during World War I, John Browning developed the .50 BMG. He wanted the round to be used in a machine gun based on a scaled-up version of the M1917 Browning.

The development of the .50 BMG round is sometimes confused with the German 13.2 mm TuF, which Germany developed for an anti-tank rifle to combat British tanks during World War I and against aircraft. According to American Rifleman: "Actually, the Browning .50 originated in the Great War. American interest in an armor-piercing cartridge was influenced by the marginal French design, prompting U.S. Army Ordnance officers to consult Browning. They wanted a heavy projectile at , but the ammunition did not exist. Browning pondered the situation and, according to his son John, replied, 'Well, the cartridge sounds pretty good to start. You make up some cartridges and we'll do some shooting.'"

The American Rifleman further explains that development was "[r]eputedly influenced by Germany's 13.2x92 mm SR (.525 in) anti-tank rifle" and that then "Ordnance contracted with Winchester to design a .50-cal. cartridge. Subsequently, Frankford Arsenal took over from Winchester, producing the historic .50 BMG (12.7×99 mm) cartridge. The Army then returned to John Browning for the actual gun. Teamed with Colt, he produced prototypes ready for testing and, ironically, completed them by Nov. 11, 1918—the Great War's end." of rolled homogeneous armor at the same range, and at .

During World War II, the .50 BMG was primarily used in the M2 Browning machine gun, in both its "light barrel" aircraft mount version and the "heavy barrel" (HB) version on ground vehicles, for anti-aircraft purposes. An upgraded variant of the M2 Browning HB machine gun used during World War II is still in use today. Since the mid-1950s, some armored personnel carriers and utility vehicles have been designed to withstand 12.7 mm machine-gun fire, thereby limiting the destructive capability of the M2. It still has more penetrating power than lighter weapons such as general-purpose machine guns, though it is significantly heavier and more cumbersome to transport. Its range and accuracy, however, are superior to light machine guns when fixed on tripods. It has not been replaced as the standard caliber for Western vehicle-mounted machine guns (Soviet and CIS armored vehicles mount 12.7×108mm NSVs, which have similar dimensions to .50 BMGs).

Decades later, the .50 BMG was chambered in high-powered rifles as well.

The U.S. Coast Guard uses .50 BMG rifles onboard armed helicopters to disable the engines on boats during interdictions. Similarly, .50 BMG weapons have attracted attention from law enforcement agencies; they have been adopted by the New York City Police Department and the Pittsburgh Police. A .50 BMG round can effectively disable a vehicle when fired into the engine block. A .50 BMG round will penetrate most commercial brick walls and concrete cinder blocks.

The .50 BMG round was used as a sniper round as early as the Korean War. Several world records for the longest confirmed kills were set with the .50 BMG. Eventually, purpose-built sniper rifles were developed specifically for this round.

In addition to long-range and anti-materiel, the U.S. military uses .50 BMG weapons to detonate unexploded ordnance from a safe distance. It can disable most unarmored and lightly armored vehicles.

Some civilians use .50 caliber rifles for long-range target shooting: the US-based Fifty Caliber Shooters Association holds .50 BMG shooting matches.

Cartridge dimensions

{| class=floatright

|thumb|right|upright|12.7×99mm NATO cartridge dimensions in inches

|thumb|upright|12.7 x 99mm NATO dimensions converted to millimeters

The .50 BMG (12.7×99mm NATO) cartridge has a capacity of . The round is a scaled-up version of the .30-06 Springfield but uses a case wall with a long taper to facilitate feeding and extraction in various weapons.

The common rifling twist rate for this cartridge is 1 in , with eight lands and grooves. The primer type specified for this ammunition is a boxer primer with a single centralized ignition point (in the U.S. and NATO countries). However, some other countries produce the ammunition with Berdan primers that have two flash holes.

The average chamber pressure in this round as listed in TM43-0001-27, the U.S. Army Ammunition Data Sheets — Small Caliber Ammunition, not including plastic practice, short cased spotter, or proof/test loads, is . The proof/test pressure is listed as .

Power

A common method for understanding the actual power of a cartridge is the comparison of muzzle energies. The .30-06 Springfield, the standard caliber for American soldiers in both World Wars and a popular caliber amongst American hunters for medium to large game animals, can produce muzzle energies between . The .50 BMG round can produce between , depending on its powder and bullet type, as well as the weapon it is fired from. Due to the high ballistic coefficient of the bullet, the .50 BMG's trajectory also suffers less "drift" from crosswinds than smaller and lighter calibers, making the .50 BMG a good choice for high-powered sniper rifles.

Military cartridge types

[[File:50BMG Rounds.jpg|thumb|upright=1.2|Left to right, rear:

Front row are 5.56×45mm NATO and .500 S&W Magnum, for size comparison]]

thumb|upright=1.2|.50 BMG rounds and projectiles. Left to right:

The .50 BMG cartridge is also produced commercially in a wide range of specifications, including armor-piercing, tracing, and incendiary:

; Cartridge, caliber .50, saboted light armor penetrator tracer (SLAP-T), M962

: Like the M903, this is a SLAP round, with the only difference being that the M962 also has a tracer element for observing fire, target designation, and incendiary purposes. It has a red plastic sabot for identification and is used only in the M2 series of machine guns.

; Cartridge, caliber .50, ball, XM1022

: A long-range match cartridge specifically designed for long-range work using the M107 rifle.

; Cartridge, caliber .50, M1022 long-range sniper

: The .50 caliber M1022 has an olive-green bullet coating with no tip ID coloration. The projectile is of standard ball design. It is designed for long-range sniper training and tactical use against targets that do not require armor-piercing or incendiary effects. It exhibits superior long-range accuracy and is trajectory matched to MK211 grade A. The M1022 is ideal for use in all .50 caliber bolt-action and semi-automatic sniper rifles. The bullet remains supersonic from to .

thumb|Raufoss Mk 211 Mod 0 HEIAP projectile

; Cartridge, caliber .50, high-explosive incendiary armor-piercing (HEIAP), Mk 211 Mod 0

: A "combined effects" cartridge, the Raufoss Mk 211 Mod 0 HEIAP cartridge contains a .30 caliber tungsten penetrator, zirconium powder, and Composition A explosive. It can be used in any .50-caliber weapon in the U.S. inventory, except the M85 machine gun. A green tip with a gray ring identified the cartridge.

; Cartridge, caliber .50, armor-piercing incendiary dim tracer (API-DT), Mk 257

: The .50 caliber Mk 257 API-DT has a purple bullet tip. The bullet has a hardened-steel core and an incendiary tip. It is used in the M2, M3, and M85. Dim tracer reduces the possibility of the weapon being located during night fire and is visible only with night-vision devices. It is identified by a gray over yellow tip. A tracer variant of it also exists.

; Cartridge, caliber .50, ball, Mk 323 Mod 0

: Created by the Naval Surface Warfare Center Crane Division, this cartridge uses M33 ball projectiles in polymer cases instead of brass. It has a clear polymer case with a standard brass head fused at the bottom. The Mk 323 can be fired from M2HB/M2A1 machine guns and GAU-21/A aircraft guns with the same performance. It gives a 25 percent weight saving over brass-cased ammunition, allowing 40 percent more ammunition to be carried for the same weight. The Mk 323's polymer casing is applied to tracer, AP, API, and SLAP projectiles.

DARPA (Defense Advanced Research Projects Agency) contracted with Teledyne Scientific Company to develop the EXACTO program, including a .50-caliber guided bullet. Videos published by DARPA show the guided bullet diverting to strike a moving target.

Belt links

Three distinct and non-compatible metallic links have been used for the .50 BMG cartridge belts. The M2 and M9 links, "pull-out" designs, are used in the Browning M2 and M3 machine guns. The M15-series metal "push-through" links were used in the M85 machine gun. Pull-out cloth belts were also used at one time, but have been obsolete since 1945.

File:M2 M9 links.gif| M2 and M9 links

File:M15A2 link.gif| M15A2 link

File:Defense.gov photo essay 120814-F-QT695-001.jpg|M9 links in use

</gallery>

Legal issues

United Kingdom

Within the United Kingdom, it is legal to own a bolt-action .50 BMG rifle with a section 1 Firearms Certificate. Applications requesting firearms in this caliber are assessed by the same criteria as smaller calibers, with the applicant having to prove they have a valid reason for owning such a weapon.

United States

The specified maximum diameter of an unfired .50 BMG bullet is ; while this appears to be over the .50 inch (12.7 mm) maximum allowed for non-sporting Title I firearms under the U.S. National Firearms Act, the barrel of a .50 BMG rifle is only .50 inch (12.7 mm) across the rifling lands and slightly larger in the grooves. The oversized bullet is formed to the bore size upon firing, forming a tight seal and engaging the rifling. Despite political controversy over the cartridge's great power (it is the most powerful commonly available cartridge not considered a destructive device under the National Firearms Act), it remains popular among long-range shooters for its accuracy and external ballistics. While the .50 BMG round can deliver accurate shot placement (if match grade ammunition is used) at ranges over , smaller-caliber rifles produce better scores and tighter groups in competitions.

A 1999 Justice Department Office of Special Investigations briefing on .50 caliber rifle crime identified several instances of the .50 BMG being involved in criminal activities. None of the cited cases has confirmed domestic violent criminal use of a .50 BMG firearm, and a majority of the domestic cases were possession charges.

In the United States, Washington, D.C. disallows registration of .50 BMG rifles, thus rendering civilian possession unlawful. California prohibits the private purchase of a rifle capable of firing the .50 BMG through the .50 Caliber BMG Regulation Act of 2004. Connecticut specifically bans the Barrett 82A1 .50 BMG rifle. However, .50 BMG rifles registered before the enacted bans remain lawful to possess in California and Connecticut. In Illinois, it is legal to possess a .50 caliber rifle only if it was acquired by January 10, 2023, and it was registered with the state police by January 1, 2024. Maryland imposes additional regulations on the sale and transfer of .50 BMG rifles and other weapons classed as "regulated firearms", and limits purchases of any firearm within this class to one per month, but does not impose registration requirements or any form of categorical ban. Writing for the Marine Corps Gazette, Major Hays Parks states: "No treaty language exists (either generally or specifically) to support a limitation on [the use of .50 BMG] against personnel, and its widespread, longstanding use in this role suggests that such antipersonnel employment is the customary practice of nations." Parks theorizes that the misconception originated in historical doctrine discouraging the use of the M8C spotting rifle—an integral .50-caliber aiming aid for the M40 recoilless rifle—in the antipersonnel role. This limitation was entirely tactical and intended to hide the vulnerable M40 and its crew from the enemy until the main anti-tank gun was ready to fire; however, Parks concludes that some U.S. troops assumed the existence of a legal limitation on the use of .50-caliber projectiles more generally.

Partial list of .50 BMG firearms

Carbines

Barrett M82CQ (a carbine version of the M82A3)

Rifles

Accuracy International AS50
Accuracy International AW50
Accuracy International AX50
ArmaLite AR-50
Arms Tech Ltd. TTR-50
Barrett M82/M107
Barrett M95
Barrett M99
Bushmaster BA50
Cadex Defence CDX-50 Tremor
Desert Tech HTI
DSR-50
Gepárd anti-materiel rifle
McMillan TAC-50
OM 50 Nemesis
PGM Hécate II
Pindad SPR-2
Ramo M600
Robar RC-50
Snipex M
Snipex Rhino Hunter
Steyr HS .50
WKW Wilk
Zastava M93 Black Arrow

Machine guns

GAU-19
GAU-21 FN M3M
M1921 Browning machine gun
M2 Browning machine gun
M85 machine gun
MAC-58 - only built as a prototype
Rolls-Royce Experimental Machine Gun - only built as prototype
STK 50MG
XM218
XM312
XM806 (LW50)
Kord machine gun - export variant
NSV machine gun - export variant of the original West Kazakhstan Machine Building Company NSV machine gun
WKM-B - Polish version of the NSV machine gun
Zastava M87 - Serbian export variant of the NSV machine gun