Question: Who was the Vickers .50 originally produced for?

full_context: Document 1: Vickers machine gun: The Vickers machine gun or Vickers gun is a name primarily used to refer to the water-cooled .303 British (7.7 mm) machine gun produced by Vickers Limited, originally for the British Army. The machine gun typically required a six to eight-man team to operate: one fired, one fed the ammunition, the rest helped to carry the weapon, its ammunition, and spare parts. It was in service from before the First World War until the 1960s, with air-cooled versions of it on many Allied World War I fighter aircraft.
Document 2: 5&quot;/38 caliber gun: The Mark 12 5"/38 caliber gun was a US naval gun. The gun was installed into Single Purpose and Dual Purpose mounts used primarily by the US Navy. On these 5" mounts, Single Purpose (SP) means that the mount is limited to 35° elevation with no provision for AA shell fuze setters, and is designed to fire at surface targets only, while Dual Purpose (DP) means that it is designed to be effective against both surface and aircraft targets because it can elevate to 85° and has on mount AA shell fuze setters. The 38 caliber barrel was a mid-length compromise between the previous United States standard 5"/51 low-angle gun and 5"/25 anti-aircraft gun. United States naval gun terminology indicates the gun fired a projectile 5 in in diameter, and the barrel was 38 calibers long, making the 5"/38 dual purpose midway in barrel length between the 5"/51 surface-to-surface and the 5"/25 anti-aircraft guns. The increased barrel length provided greatly improved performance in both anti-aircraft and anti-surface roles compared to the 5"/25 gun. However, except for the barrel length and the use of semi-fixed ammunition, the 5"/38 gun was derived from the 5"/25 gun. Both weapons had power ramming, which enabled rapid fire at high angles against aircraft. The 5"/38 entered service on USS "Farragut" , commissioned in 1934. The base ring mount, which improved the effective rate of fire, entered service on USS "Gridley" , commissioned in 1937.
Document 3: M1917 Browning machine gun: The M1917 Browning machine gun is a heavy machine gun used by the United States armed forces in World War I, World War II, Korea, and to a limited extent in Vietnam; it has also been used by other nations. It was a crew served, belt-fed, water-cooled machine gun that served alongside the much lighter air-cooled Browning M1919. It was used at the battalion level, and often mounted on vehicles (such as a jeep). There were two main iterations of it: the M1917, which was used in World War I; and the M1917A1; which was used thereafter. The M1917, which was used on some aircraft as well as in a ground role, had a cyclic rate of 450 rounds per minute; the M1917A1 had a cyclic rate of 450 to 600 rounds per minute.
Document 4: MAC-58: The MAC-58 was a version of the French AA-52 machine gun chambered in .50 BMG instead of 7.62×51mm NATO. A few prototypes were tested and one retained for preserial production, but it never reached production due to the large quantity of US M2 Browning machine guns already in service with the French armed forces.
Document 5: 5&quot;/54 caliber Mark 42 gun: The Mark 42 5"/54 caliber gun (127mm) is a naval gun (naval artillery) mount used by the United States Navy and other countries. It consisted of the Mark 18 gun and Mark 42 gun mount. United States naval gun terminology indicates the gun fires a projectile 5 in in diameter, and the barrel is 54 calibers long (barrel length is 5" × 54 = 270" or 6.9 meters.) In the 1950s a gun with more range and a faster rate of fire than the 5"/38 caliber gun used in World War II was needed, therefore, the gun was created concurrently with the 3"/70 Mark 26 gun for different usages. The 5"/54 Mk 42 is an automatic, dual-purpose (air / surface target) gun mount. It is usually controlled remotely from the Mk 68 Gun Fire Control System, or locally from the mount at the One Man Control (OMC) station.
Document 6: QF 2.95-inch Mountain Gun: The QF 2.95 inch mountain gun was the designation given by the British to a Vickers 75mm calibre gun. It was originally produced for the Egyptian Army. It was taken into British service in the late 19th Century to provide the 'movable armament' at some coaling stations. Also known as 'The Millimetre Gun', it was used by the West African Frontier Force in several theatres in Africa during World War I. It was also used by USA and Philippines.
Document 7: Type 77 heavy machine gun: The Type 77 heavy machine gun is described as China’s first generation designed 12.7 mm heavy machine gun. The Type 85 is a “product improved” version. The weapon is both gas (three settings) and recoil operated. The ammunition belt is the standard DShK metal non-disintegrating link.
Document 8: Machine gun: A machine gun is a fully automatic mounted or portable firearm designed to fire bullets in quick succession from an ammunition belt or magazine, typically at a rate of 300 to 1800 rounds per minute. Not all fully automatic firearms are machine guns. Submachine guns, rifles, assault rifles, shotguns, pistols or cannons may be capable of fully automatic fire, but are not designed for sustained fire. As a class of military rapid-fire guns, machine guns are fully automatic weapons designed to be used as support weapons and generally used when attached to a mount or fired from the ground on a bipod or tripod. Many (but not all) machine guns also use belt feeding and open bolt operation, features not normally found on rifles.
Document 9: M3 submachine gun: The M3 was an American .45-caliber submachine gun adopted for U.S. Army service on 12 December 1942, as the United States Submachine Gun, Cal. .45, M3. The M3 was chambered for the same .45 round fired by the Thompson submachine gun, but was cheaper to produce, and lighter, although, contrary to popular belief, it was far less accurate. This myth stems from a US army training film portraying the M3 as more accurate than its counterparts. The M3 was commonly referred to as the "Grease Gun" or simply "the Greaser," owing to its visual similarity to the mechanic's tool.
Document 10: Vickers .50 machine gun: The Vickers .50 machine gun, also known as the 'Vickers .50' was basically similar to the .303 in Vickers machine gun but scaled up to use a larger-calibre 0.5 in round. It saw some use in tanks and other fighting vehicles, but was much more commonly used as a close-in anti-aircraft weapon on Royal Navy and allied ships, typically in a four-gun mounting. The Vickers fired UK 12.7×81mm 50-calibre ammunition, not the better known US 12.7×99mm (.50 BMG).
Document 11: QF 2-pounder naval gun: The 2-pounder gun, officially designated the QF 2-pounder (QF denoting "quick firing") and universally known as the pom-pom, was a 40 mm British autocannon, used as an anti-aircraft gun by the Royal Navy. The name came from the sound that the original models make when firing. This QF 2-pounder was not the same gun as the Ordnance QF 2 pounder, used by the British Army as an anti-tank gun and a tank gun; they shared only the projectile weight of 2 pounds.
Document 12: M45 Quadmount: The M45 Quadmount (nicknamed the "meat chopper" and "Krautmower" for its high rate of fire) was a weapon mounting consisting of four of the "HB", or "heavy barrel" .50 caliber M2 Browning machine guns (of the M2 Turret Type (TT) variant) mounted in pairs on each side of an open, electrically powered turret. It was developed by the W. L. Maxson Corporation to replace the earlier M33 twin mount (also from Maxson). Although designed as an anti-aircraft weapon, it was also used against ground targets. Introduced in 1943 during World War II, it remained in US service as late as the Vietnam War.
Document 13: M2 Browning: The M2 Machine Gun or Browning .50 Caliber Machine Gun is a heavy machine gun designed toward the end of World War I by John Browning. Its design is similar to Browning's earlier M1919 Browning machine gun, which was chambered for the .30-06 cartridge. The M2 uses the much larger and much more powerful .50 BMG cartridge, which was developed alongside and takes its name from the gun itself (BMG standing for "Browning Machine Gun"). It has been referred to as "Ma Deuce", in reference to its M2 nomenclature. The design has had many specific designations; the official designation for the current infantry type is Browning Machine Gun, Cal. .50, M2, HB, Flexible. It is effective against infantry, unarmored or lightly armored vehicles and boats, light fortifications and low-flying aircraft. The M2 has been produced longer than any other machine gun.
Document 14: Squad automatic weapon: A squad automatic weapon (SAW, also known as section automatic weapon or light support weapon) is a weapon used to give infantry squads or sections a portable source of fully automatic firepower. Weapons used in this role are often selective fire rifles, usually fitted with a bipod and heavier barrel to perform as light machine guns. Squad automatic weapons usually fire the same cartridge as the assault rifles or battle rifles carried by other members of the unit. This reduces logistical requirements by making it only necessary to supply one type of ammunition to a unit. Squad automatic weapons are light enough to be operated by one person, as opposed to heavy machine guns such as the M2 Browning, which fire more powerful cartridges but require a crew to operate at full effectiveness.
Document 15: .50 BMG: 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 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. 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 linked using metallic links.
ground_truth: the British Army