Seputar Kaliber 50

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.^{[citation needed]} 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.^[1] This record was surpassed in 2009 in Afghanistan by a British sniper, though using a .338 Lapua Magnum (8.58×70 mm) rifle.^[2][3] A former record for a confirmed long-distance kill was set by US Marine sniper Carlos Hathcock in 1967, the distance was 2,286 meters (2,500 yards, 7,500 feet) or 1.42 miles (2.29 km). 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 developed the EXACTO program, .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.
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,^{[citation needed]} based on a scaled-up .30-06 Springfield design,^{[citation needed]} 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.^[4]
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. However, after some analysis the German ammunition was ruled out, both because performance was inferior to the modified Springfield .30-06 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).^[5]
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.

The .50 BMG cartridge.

During World War II the .50 BMG was primarily used in the M2 Browning machine gun for anti-aircraft purposes. An upgraded variant of the M2 Browning 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 12.7 mm DShK, NSV, which are ballistically very similar to the .50 BMG, but 14.5 mm KPV machine guns have significantly superior armor penetration compared to any 12.7 mm round. Despite this advantage, The accuracy of the 14.5x114mm round degrades rapidly at ranges beyond 1000 meters^[6])
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.

[edit] Power

A common method for understanding the actual power of a cartridge is by comparing muzzle energies. The Springfield .30-06, the standard caliber for American soldiers in both World Wars and a popular caliber amongst American hunters, can produce muzzle energies between 2000 and 3000 foot pounds of energy (between 3 and 4 kilojoules). A .50 BMG round can produce between 10,000 and 15,000 foot pounds (between 14 and 18 kilojoules) or more, depending on its powder and bullet type, as well as the rifle it was 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. Although the .50 BMG is balisticaly inferior to the Russian 12.7×108mm, it is still marginally effective against light vehicle armour.^{[citation needed]}

[edit] Cartridge dimensions

These measurements are not suggested for reloading use.

The 50 BMG 12.7 × 99 NATO cartridge has a capacity of 290 grains H₂O (19 ml). 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.
50 BMG basic cartridge dimensions. All sizes in inches (in). The common rifling twist rate for this cartridge is 1 in 15 in (381 mm), with 8 lands and grooves. The primer type specified for this ammunition is 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.
Average chamber pressure in for this round as listed in TM43-0001-27^[7] 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 MPa or 3,787 bar). The proof/test pressure is listed as 65,000 psi (448 MPa or 4,482 bar). As a note these are the military machine gun standards and not ideal for use as guidelines in reloading or personal use.