.50 BMG
From Freepedia
The .50 Browning Machine Gun (12.7×99 mm NATO) or .50 BMG is a cartridge developed for the M2 machine gun and is now also used in long-range target and sniper rifles. The actual specified maximum diameter of an unfired .50 BMG bullet is .51 inches; while this appears to be over the .50 inch (12.7 mm) maximum allowed under the National Firearms Act, the barrel of a .50 BMG rifle is only .50 inches across the rifling lands, and slightly larger in the grooves. The oversized bullet is swaged to size upon firing, forming a tight seal and engaging the rifling. While subject to current 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 is popular among long range shooters for its accuracy and external ballistics, and it is one of the few cartridges that delivers accuracy (if match grade ammunition is used) at ranges over 1000 yards (.9 km).
A wide variety of ammunition is available including ball, tracer, armor piercing, incendiary and saboted sub-caliber rounds. The availability of match grade ammunition has increased the usefulness of .50 caliber rifles by allowing more accurate fire than lower quality rounds. Matching the availability and price of the higher-quality .50 ammunition is an impediment to producing large caliber rifles using a different round such as 20 mm or another custom size.
History
During World War 2 it found its usage in penetrating lightly armoured vehicles, including aircraft. An upgraded variant of the Browning machine gun used during World War 2 is still in use today as the well known M2 machine gun. Since the mid-1950s, armoured 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 machine guns, but is difficult to maintain and aim in field conditions. Its range and accuracy, however, are superior to light machine guns when fixed and water cooled, and 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, or 14.5 mm KPV machine guns, which have superior armour penetration).
The Barret M82 .50 Caliber rifle and later variants were born during the 1980s and have upgraded the military sniper from a heavy nuisance to a threat. A skilled sniper can effectively neutralize an infantry unit by picking off several soldiers at a very long range, without revealing his precise location, then spend a few hours moving to a new position (whether they decide to hunt down the sniper or to retreat), before firing again. However, due to their high cost and the relative inaccuracy of the recoil-operated Barrets, such heavy-caliber sniper rifles are considered anti-material weapons.
A Canadian sniper in Afghanistan used a .50 BMG rifle to kill a Taliban guerilla at 2430m [1] during Operation Anaconda.
.50 BMG ammunition has even been used in some handguns such as the Maadi-Griffin handgun and Thunder 50 handgun. They have much shorter barrels than rifles firing the round, so do not have the same power.
