|Type||Heavy machine gun/Anti-materiel rifle|
|Place of origin||United States|
|Used by||NATO and many other countries|
|Wars||World War II|
Cambodian Civil War
Persian Gulf War
Global War on Terrorism
War in Afghanistan
Syrian Civil War
Iraqi Civil War (2014-2017)
Yemeni Civil War (2015-present)
Saudi Arabian-led intervention in Yemen
Saudi-Yemeni border conflict (2015-present)
|Designer||Winchester Repeating Arms Co. and Frankford Arsenal|
|Case type||Rimless, bottleneck|
|Bullet diameter||.510 in (13.0 mm)|
|Neck diameter||.560 in (14.2 mm)|
|Shoulder diameter||.735 in (18.7 mm)|
|Base diameter||.804 in (20.4 mm)|
|Rim diameter||.804 in (20.4 mm)|
|Rim thickness||.083 in (2.1 mm)|
|Case length||3.91 in (99 mm)|
|Overall length||5.45 in (138 mm)|
|Case capacity||292.8 gr H2O (18.97 cm3)|
|Primer type||#35 Arsenal Primer|
|Maximum pressure (TM43-0001-27)||54,923 psi (378.68 MPa)|
|Maximum pressure (EPVAT)||60,481 psi (417.00 MPa)|
|Maximum pressure (C.I.P.)||53,664 psi (370.00 MPa)|
|Test barrel length: 45 in (1,100 mm)|
Source(s): Ammoguide.com 
The .50 Browning Machine Gun (.50 BMG, 12.7×99mm NATO and designated as the 50 Browning by the C.I.P.) is a cartridge developed for the Browning .50 caliber machine gun in the late 1910s, entering official service in 1921. Under STANAG 4383, it is a standard cartridge for NATO forces as well as many non-NATO countries. The cartridge itself has been made in many variants: multiple generations of regular ball, tracer, armor-piercing (AP), incendiary, and saboted sub-caliber rounds. The rounds intended for machine guns are made into a continuous belt using metallic links.
The .50 BMG cartridge is also used in long-range target and anti-materiel rifles, as well as other .50-caliber machine guns.
A wide variety of ammunition is available, and the availability of match grade ammunition has increased the usefulness of .50 caliber rifles by allowing more accurate fire than lower quality rounds.
John Browning had the idea for this round during World War I in response to a need for an anti-aircraft weapon, based on a scaled-up .30-06 Springfield design, used in a machine gun based on a scaled-up M1919/M1917 design that Browning had initially developed around 1900 (but which was not adopted by the U.S. military until 1917, hence the model designation). Armor-piercing incendiary tracer (APIT) rounds were especially effective against aircraft, and the AP rounds and armor-piercing incendiary (API) rounds were excellent for destroying concrete bunkers, structures, and lighter armored fighting vehicles (AFVs). The API and APIT rounds left a flash, report, and smoke on contact, useful in detecting strikes on targets.
The development of the .50 BMG round is sometimes confused with the German 13.2 mm TuF, which was developed by Germany for an anti-tank rifle to combat British tanks during WWI and against aircraft. According to the American Rifleman: "Actually, the Browning .50 originated in the Great War. American interest in an armor-piercing cartridge was influenced by the marginal French 11 mm design, prompting U.S. Army Ordnance officers to consult Browning. They wanted a heavy projectile at 2700 feet per second (f.p.s.), 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 (.53-cal.) 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 or 12.7x99 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."
The round was put into use in the M1921 Browning machine gun. This gun was later developed into the M2HB Browning which with its .50 caliber armor-piercing cartridges went on to function as an anti-aircraft and anti-vehicular machine gun, capable of penetrating 0.9 inches (23 mm) of face-hardened armor steel plate at 200 meters (220 yd), 1 inch (25 mm) of rolled homogeneous armor at the same range, and 0.75 inches (19 mm) at 547 yards (500 m).
The concept of a .50 caliber machine gun was not an invention of this era; this caliber (.50 inch) had been used in Maxim machine guns and in a number of manual rapid-fire guns such as the original Gatling gun, although these were much lower power cartridges.
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 made to withstand 12.7 mm machine gun fire, restricting 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, and 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 are ballistically similar to .50 BMGs).
Decades later, the .50 BMG was chambered in high-powered rifles as well. The Barrett M82 .50 caliber rifle and later variants were developed during the 1980s and have upgraded the anti-materiel power of the military sniper. A skilled sniper can effectively neutralize an infantry unit by eliminating several targets (soldiers or equipment) without revealing his precise location. The long range (over one mile) between firing position and target allows time for the sniper to avoid enemy retaliation by either changing positions repeatedly, or by safely retreating.
A common method for understanding the actual power of a cartridge is 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, can produce muzzle energies between 2,000 and 3,000 foot-pounds force (3,000 and 4,000 J). The .50 BMG round can produce between 10,000 and 15,000 foot-pounds force (14,000 and 20,000 J), 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 cross-winds than smaller and lighter calibers, making the .50 BMG a good choice for high-powered sniper rifles.
The .50 BMG (12.7×99mm NATO) cartridge has a capacity of 290 grains (19 ml H2O). 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 15 in (380 mm), with eight lands and grooves. The primer type specified for this ammunition is a boxer primer that has a single centralized ignition point (US 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 54,923 psi (378,680 kPa). The proof/test pressure is listed as 65,000 psi (450,000 kPa).
The .50 BMG cartridge is also produced commercially with a plethora of different bullets and to a number of different specifications.
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.
Two distinct and non-compatible metallic links have been used for the .50 BMG cartridge, depending upon the machine gun which will be firing the cartridges. The M2 and M9 links, "pull-out" designs, are used in the Browning M2 and M3 machine guns. Pull-out cloth belts were also used at one time, but have been obsolete since 1945. The M15-series "push-through" links were used in the M85 machine gun.
The specified maximum diameter of an unfired .50 BMG bullet is 0.510-inch (13.0 mm); 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, a mechanism which in firearm terms is known as swaging. Subject to political controversy due to the great power of the cartridge (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 is able to deliver accurate shot placement (if match grade ammunition is used) at ranges over 1,000-yard (910 m), smaller caliber rifles produce better scores and tighter groups in 1,000-yard (910 m) competitions.
In response to legal action against the .50 BMG in the United States and Europe, an alternative chambering was developed. The .510 DTC Europ uses the same bullet, but has slightly different case dimensions. .510 DTC cases can be made by fire-forming .50 BMG cases in a .510 DTC chambered rifle. The new round has almost identical ballistics, but because of the different dimensions, rifles chambered for .50 BMG cannot fire the .510 DTC, and therefore rifles chambered for .510 DTC do not fall under many of the same legal prohibitions. Barrett offers a similar alternative, the .416 Barrett, which is based on a shortened .50 BMG case necked down to .416 caliber (10.3 mm).
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. Most of the instances of criminal activity cited in the Office of Special Investigations briefing involved the illegal possession of a .50 BMG rifle. The briefing did not identify any instance of a .50 BMG rifle being used in the commission of a murder.
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 prior to the enacted bans remain lawful to possess in California and Connecticut.Maryland imposes additional regulations on the sale and transfer of .50 BMG rifles and other "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.
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.
Contrary to a persistent misconception within the United States Armed Forces, using .50 BMG directly against enemy personnel is not prohibited by the laws of war. Writing for the Marine Corps Gazette, Maj Hays Parks states that "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 in nature and was intended to hide the vulnerable M40 and its crew from the enemy until the main anti-tank gun was ready for firing; however, Parks concludes that some U.S. troops assumed the existence of a legal limitation on the use of .50-caliber projectiles more generally.
The U.S. Coast Guard uses .50 BMG rifles to disable outboard engines from armed helicopters during interdictions. Similarly, .50 BMG weapons have attracted attention from law enforcement agencies; they have been adopted by the New York City Police Department as well as the Pittsburgh Police. A .50 BMG round can effectively disable a vehicle when fired into the engine block. If it is necessary to breach barriers, a .50 BMG round will penetrate most commercial brick walls and concrete cinder blocks.
The .50 BMG round has been used as a sniper round as early as the Korean War. The former record for a confirmed long-distance kill was set by U.S. Marine sniper Carlos Hathcock in 1967 during the Vietnam War, at a distance of 2,090 meters (2,290 yd; 1.30 mi); Hathcock used the .50 BMG in an M2 Browning Machine Gun equipped with a telescopic sight. This weapon was used by other snipers, and eventually purpose-built sniper rifles were developed specifically for this round.
In June 2017, a McMillan Tac-50 was used by a sniper with Canada's Joint Task Force 2 to kill an Islamic State insurgent in Iraq, setting the world record for the longest confirmed kill shot in military history at 3,540 meters (3,870 yd; 2.20 mi). Before that record, Canadian Army Corporal Rob Furlong of the PPCLI achieved what was then the longest-range confirmed sniper kill in history when he shot a Taliban combatant at 2,430 meters (2,660 yd; 1.51 mi) during the 2002 campaign in the Afghanistan War. This was surpassed in 2009 by a British sniper in Afghanistan with 2,475 meters (2,707 yd; 1.538 mi) using a .338 Lapua Magnum (8.58×70 mm) rifle.
In addition to long-range and anti-materiel sniping, 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.
...any person who has a Certificate of Possession issued by the Special Licensing and Firearms Unit may possess the Assault Weapon listed on their certificate.... a Certificate of Possession must be obtained prior to January 1, 2014