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The .50 Browning Machine Gun (.50 BMG) or 12.7×99mm NATO is a cartridge developed for the Browning .50 caliber machine gun in the late 1910s. Entering service officially in 1921, the round is based on a greatly scaled-up .30-06 cartridge. Under STANAG 4383, it is a standard cartridge for NATO forces as well as many non-NATO countries.〔(NATO Infantry Weapons Standardization, Per G. Arvidsson, ChairmanWeapons & Sensors Working GroupLand Capability Group 1 - Dismounted Soldier NATO Army Armaments Group )〕 The cartridge itself has been made in many variants: multiple generations of regular ball, tracer, armor piercing, incendiary, and saboted sub-caliber rounds. The rounds intended for machine guns are linked using metallic links. The .50 BMG cartridge is also used in long-range target and sniper rifles, as well as other .50-caliber machine guns. The use in single-shot and semi-automatic rifles has resulted in many specialized match-grade rounds not used in .50-caliber machine guns. A McMillan Tac-50 .50 BMG sniper rifle was used by Canadian Army Corporal Rob Furlong of the PPCLI to achieve what was then the longest-range confirmed sniper kill in history, when he shot a Taliban combatant at 2,430 meters (2,657 yards) during the 2002 campaign in the Afghanistan War. This record was surpassed in 2009 in Afghanistan by a British sniper with 2,475 meters (2,707 yards) though using a .338 Lapua Magnum (8.58×70 mm) rifle. A former record for a confirmed long-distance kill was set by U.S. Marine sniper Carlos Hathcock in 1967, at a distance of ; 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. DARPA (Defense Advanced Research Projects Agency) has contracted with Lockheed Martin to develop the EXACTO program, including .50-caliber bullets complete with microprocessors and steering vanes that allow the bullet to adjust its trajectory mid-flight to stay on target when the flight path has been altered by uncontrollable variables, as well as weapons that fire these rounds and monitor their flight. The weapon system is expected to be available in 2015. 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. ==History== 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 API rounds were excellent for destroying concrete bunkers, structures, and lighter AFVs. The API and APIT rounds left a flash, report, and smoke on contact, useful in detecting strikes on enemy targets.〔Dunlap, Roy F., ''Ordnance Went Up Front'', Samworth Press (1948), pp. 311–312.〕 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; however, the development of the U.S. .50 caliber round was started before this later German project was completed or even known to the Allied countries. When word of the German anti-tank round spread, there was some debate as to whether it should be copied and used as a base for the new machine gun cartridge; after some analysis the German ammunition was ruled out, both because performance was inferior to the scaled-up .30-06 Springfield round and because it was a semi-rimmed cartridge, making it sub-optimal for an automatic weapon. The round's dimensions and ballistic traits are totally different. Instead, the M2HB Browning with its .50 caliber armor-piercing cartridges went on to function as an anti-aircraft and anti-vehicular machine gun, with a capability of completely perforating 0.875" (22.2 mm) of face-hardened armor steel plate at 100 yards (91 m), and 0.75" (19 mm) at 547 yards (500 m).〔Barnes, Frank C., ''Cartridges of the World'', U.S. Army .50 BMG Cartridge Specifications, DBI Books (1989), ISBN 978-0-87349-033-7, p. 432.〕 Decades later, the .50 BMG was chambered in high-powered rifles as well. The concept of a .50 caliber machine gun was not an invention of this era; this caliber (.50) had been used in Maxim machine guns and in a number of manual rapid fire guns such as the original Gatling, 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, thus making it a much less flexible weapon. 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 armoured vehicles mount the 12.7×108mm NSV, which is ballistically similar to the .50 BMG.) The Barrett M82 .50 caliber rifle and later variants were born 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 (1 mile+) between firing position and target allows time for the sniper to avoid enemy retribution by either changing positions repeatedly, or by safely retreating. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「.50 BMG」の詳細全文を読む スポンサード リンク
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