[21] Vickers was threatened with prosecution for war profiteering, due to the exorbitant price demanded for each gun.

As the war progressed, and numbers increased, it became the British Army's primary machine gun, and was used on all fronts during the conflict.

After the First World War, the Machine Gun Corps (MGC) was disbanded and the Vickers returned to infantry units.

[13] Its successor in UK service is the British L7 variant of the FN MAG general purpose machine gun.

However, by the time the production version, the Vickers F.B.5, had entered service the following year, the armament had been changed to a Lewis gun.

[23] During World War I, the Vickers gun became a standard weapon on British and French military aircraft, especially after 1916, initially in a single gun configuration (Nieuport 17, SPAD VII, Sopwith Triplane), increased to a twin-gun standard in later war fighters (Nieuport 28, SPAD XIII, Sopwith Camel), with exceptions such as the S.E.5, which had a single synchronized Vickers and a Lewis gun mounted above the upper wing.

Steel disintegrating-link ammunition belts were perfected in the UK by William de Courcy Prideaux in mid-war and became standard for aircraft guns thereafter.

[25][26] The famous Sopwith Camel and the SPAD XIII types used twin synchronized Vickers, as did most British and French fighters between 1918 and the mid-1930s.

In the air, the weighty water-cooling system was rendered redundant by low temperatures at high altitude and the constant stream of air passing over the gun (and lack of any need for sustained fire such as employed by ground troops); but because the weapon relied on boosted barrel recoil, the (empty) water-holding barrel jacket or casing was retained.

Several sets of louvered slots were cut into the barrel jacket to aid air cooling, a better solution than that which had initially been attempted with the 1915-vintage lMG 08 German aircraft ordnance.

[28] As the machine gun armament of US and UK fighter aircraft moved from the fuselage to the wings in the years before World War II, the Vickers was generally replaced by the faster-firing and more reliable[29] Browning Model 1919 using metal-linked cartridges.

Vickers machine guns, designated as models E (pilot's) and F (observer's, fed from a pan magazine) were also used among others in Poland, where 777 of them were converted to 7.92×57mm Mauser cartridge in 1933–1937.

Firing either single shot or automatic it had a pistol type trigger grip rather than the spades of the 0.303 in (7.7 mm) weapon.

Intended for British light tanks, some were used during the war on mounts on trucks by the Long Range Desert Group in the North Africa Campaign.

For example: The Union of South Africa retained a large inventory of surplus Vickers machine guns after World War II.

[38] Small quantities re-chambered for 7.62 mm NATO ammunition remained in active service with the South African Defence Force until the mid-1980s, when they were all relegated to reserve storage.

[38] Six were withdrawn from storage and reused by a South African liaison team operating with UNITA during the Battle of Cuito Cuanavale, after which the weapons were finally retired.

The Board of Ordnance & Fortifications held a meeting on March 15, 1913 to consider the adoption of a new type of machine gun.

The Board is of the unanimous opinion that the Vickers rifle caliber gun, light model, stood the most satisfactory test.

[49] In 1940 and 1941, a total of 7,071 M1915 guns were purchased by the United Kingdom[50] to re-equip their forces after the Dunkirk evacuation, which depleted the weapon from the U.S. inventory before their entry into the war.

The resulting steam was taken off by a flexible tube to a condenser container—this had the dual benefits of avoiding giving away the gun's location, and also enabling re-use of the water, which was very important in arid environments.

In British service, the Vickers gun fired the standard .303 inch cartridges used in the Lee–Enfield rifle, which generally had to be hand-loaded into the cloth ammunition belts.

In practice, it was expected that 10,000 rounds would be fired per hour, and that the barrel would be changed every hour—a two-minute job for a trained team.

One account states that a Vickers fired just under 5 million rounds in a week as a test in 1963 at Strensall Barracks and was still operable.

The evaporative cooling system, though heavy, was very effective and enabled the gun to keep firing far longer than its air-cooled rival weapons.

[52] It was sometimes claimed that crews would fire off a few rounds simply to heat their gun's cooling water to make tea, despite the resulting brew tasting of machine-oil.

The only similar weapon of the time to use indirect fire was the German MG 08, which had a separate attachment sight with range calculator.

When operated, the floating action, which consists of the barrel, breechblock assembly and toggle mechanism, reciprocate as a unit within the body of the gun.

When the breechblock assembly unlocks after firing, the extractor pulls the spent cartridge from the chamber and, once clear, this falls through an ejection port in the underside of the gun's body.

As the breechblock assembly fully closes on the breech, the sear disengages but the firing pin is held rearward by the trigger.