Development and Early Stages
In 1925, the Vickers corporation acquired the rights to all designs from the French firm Berthier, releasing a limited series of new light machine guns known as “Vickers-Berthier,” sometimes designated as “Vickers class L.” This production was initiated by Vickers management, without a state order, to occupy the unutilized manufacturing capacity of the Crayford plant and in the hope of future government contracts. By the mid-1920s, it was clear that the standard Lewis light machine gun, then in service, was becoming obsolete with no adequate replacement in the British army.
The first Vickers-Berthier machine guns from the Crayford factory did not interest the English military but participated in competitive trials in many Balkan states and the East Indies. The Latvian army purchased a batch, though their fate after Latvia’s annexation to the USSR remains unknown as they were not adopted by the Red Army. During comparative tests in the Dutch East Indies, the Vickers-Berthier performed excellently, but the Dutch did not sign a contract, preferring the old, proven, and, crucially, free Lewis for economy.
Spain acquired a batch for use in Morocco, and several South American countries also bought small quantities. Its largest user, however, was the Indian army, which officially adopted it and established a production line for the Vickers-Berthier Mk.III at the Ishapore arms factory. The British mainland, meanwhile, rejected the new machine gun, preferring the Bren gun, which was very similar to the Vickers-Berthier in both appearance and technical specifications, becoming the standard British army light machine gun for the next 20 years. Despite modest overall sales, the Vickers-Berthier helped the Vickers company survive the financial crisis in the UK in the late 1920s.
Innovative Features and Adoption
In an attempt to rebound from the light machine gun’s initial setback, Vickers sought to adapt the Vickers-Berthier for aviation use, a decision driven more by the corporation’s financial state than by military necessity. During this period, the aviation command was in an “interwar hibernation” and content with the WWI-era Vickers and Lewis machine guns already in service. In 1928, the company attempted to interest the Royal Air Force (RAF) with a new machine gun designated “Vickers GO” (gas operated), positioning it as an ideal defensive weapon for observer-gunners.
The extensive advertising campaign emphasized the machine gun’s extreme simplicity and very low recoil. Its main components could be assembled and disassembled without any tools and were designed such that incorrect assembly was impossible. The primary moving parts were well-protected from adverse weather conditions, and the weapon’s design was very clean, without protruding moving parts that could hinder operation during firing.
The recoil was so light that a gunner could easily hold the machine gun while firing long bursts, reliably placing a 97-round disc magazine into a 1.5-meter circle from a distance of 150 meters. In case of overheating, the barrel could be replaced by an experienced gunner within five seconds, without touching it or disassembling other parts of the machine gun. Vickers recommended barrel replacement after 240 rounds in a long burst; however, if necessary in combat, firing could continue with only a slight loss of accuracy. Vickers also offered a heavy barrel option for significantly higher heat resistance during prolonged barrage fire with long bursts. All Vickers GO components were interchangeable, and the machine gun featured a selector for both single and burst fire.
Vickers designers, well aware of the potential consequences of an in-flight machine gun failure, did everything possible to minimize these problems. All rapidly wearing parts could be replaced in the air without tools, and partial assembly/disassembly took less than 30 seconds. Another significant advantage was that the bolt remained open when firing ceased, eliminating the possibility of a cartridge cook-off in a hot chamber and improving barrel cooling through air circulation.
The original 97-round .303” disc magazine, when fully loaded, weighed 11.75 pounds (5.3 kg). It outwardly resembled the Lewis machine gun’s disc but, unlike the latter, remained fixed on top of the receiver without rotating during firing. Cartridges were fed by a pre-wound spiral spring. The Vickers GO also incorporated an ammunition counter – a very useful feature in combat. This was a flag attached to the magazine’s feed spring, which moved as ammunition was expended, allowing the gunner to always see how many rounds remained. Compared to its prototype, the Vickers-Berthier light machine gun, the aviation version’s rate of fire was increased to 950 rounds/min, achieved by enlarging the gas port hole and using a more powerful buffer to compensate for the recoil energy of the moving parts. For use in defensive installations, it was designed for mounting in standard “Scarff ring” installations, in both single and twin configurations.
Wartime Service and Legacy
Despite the machine gun’s high performance, its adoption process dragged on for several years. It was only in late 1934, finally realizing that “Vickers class F” machine guns no longer met modern requirements, that RAF command officially adopted the “Vickers GO” under the designation “Vickers class K.” The name “Vickers GO” or “VGO” was also widely used.
The Vickers GO was a highly progressive weapon at the time of its creation: light, reliable, and with a high rate of fire. Indeed, it was an ideal weapon for gunners in open-cockpit bombers and reconnaissance aircraft of the 1920s and early 1930s. However, as often happens, with the revolution in aircraft design in the second half of the 1930s, the machine gun quickly became obsolete. The new generation of bombers featured powered, mechanized gun installations that made it practically impossible to accommodate machine guns with disc magazines. Military requirements to install two or more machine guns in bomber turrets left the almost new English machine gun at a disadvantage. There was little room for disc magazines in the turrets, and the “Vickers class K” could not be quickly re-engineered for belt feed. Consequently, in the late 1930s, American “Colt-Browning” machine guns, produced under license in the UK, began to be introduced into bomber defensive installations.
Although it was already evident by the time of its adoption that the “Vickers class K” was outdated, Britain, on the eve of the impending war, was left with a huge inventory of WWI-era aviation machine guns and no prospects for rapid rearmament. Given this situation, the RAF leadership was grateful for any option. The “Vickers class K” was adopted by the RAF for a number of light bombers and reconnaissance aircraft and also kept in reserve. Its operating and maintenance manuals were printed and preserved throughout World War II. Just before the war, there was even an attempt to adapt the “Vickers GO” as a fixed offensive weapon, for which special drum magazines with capacities of 300 and 600 rounds were developed. However, due to their size, the idea did not gain traction.
The “Vickers-K” remained in service with the RAF and Royal Navy as defensive armament on bombers such as the Fairey “Battle,” Handley Page “Hampden,” Bristol “Blenheim,” in the nose turret of the “Whitley,” and on deck-landing aircraft like the Fairey “Swordfish,” Fairey “Albacore,” and Fairey “Barracuda,” lasting until the end of World War II.
From mid-war, well-preserved examples of “Vickers-K” machine guns, removed from aircraft, began to be transferred to ground units of the RAF for airfield defense, where they were typically mounted on various improvised anti-aircraft stands. However, the “Vickers-K” machine guns gained their greatest notoriety in the hands of the newly formed British special forces units, the SAS (Special Air Service). SAS operators discovered that the reliable, high-rate-of-fire “Vickers G.O.” guns were excellent weapons for use on light all-terrain vehicles (Jeeps) during “hit-and-run” raids against Germans and Italians, following special forces tactics.
Similarly, “Vickers G.O.” machine guns were used by British special forces operating in North Africa, known as the “Desert Rats” (officially the LRDG – Long Range Desert Group). The machine guns used by SAS, LRDG, and other British commando units in 1943-44-45 largely retained their original “aviation” appearance and were mounted on Jeeps using a variety of, mostly improvised, single and twin mounts. Around 1943, however, a special “infantry” variant of this machine gun appeared: the “Vickers G.O. No.2 Mk.1 Land service.” Initially developed for airfield defense units, it was used by British commando units in the final stages of the war (1944-45), primarily in the European Theater of Operations. This new variant was created by converting original aviation machine guns. Almost immediately after the end of World War II, this machine gun was withdrawn from service and no longer participated in combat.
Operating Principles
The automatic action of the “Vickers-K” (Vickers GO) machine gun is based on tapping a portion of the powder gases, diverted through a gas tube under the barrel. These gases act on a gas piston, which then locks the next round into the barrel chamber by tilting the bolt. The barrel is air-cooled and quick-change. Ammunition is fed from a top-mounted, double-row disc magazine with a nominal capacity of 100 rounds (usually no more than 96-97 rounds were recommended to increase feeding reliability). In the aviation version, the machine gun was equipped with a characteristic vertical pistol grip with the trigger on the rear of the receiver. The machine gun’s automation provided a rate of fire of 950-1200 rounds/min (usually no more than 950 rounds/min), its loaded weight was 13.4 kg, unloaded 9.5 kg, and the muzzle velocity was 762 m/s.
The loaded magazine was attached to the recess on the top of the receiver until it locked. The bolt charging handle, on the left side, was pulled back and then pushed forward. The firing mode selector, located on the right rear of the receiver, was set to automatic mode. This action rotated one of two sears, which blocked the piston, downwards. The other sear was released when the trigger was pressed, allowing the bolt to move from the cocked position.
Propelled forward by the energy of the compressed recoil spring, the upper part of the bolt face extracts a cartridge from the magazine and begins to feed it into the chamber. During this action, the extractor rides over the rim of the cartridge case and engages the groove in the lower part of the case. Coinciding with reaching its extreme forward movement, the rear part of the bolt slightly extends beyond the locking lug, which is machined into the upper part of the receiver. The bolt has a recess in its rear part, in which the lifting lug of the cross-piece moves. This entire structure is connected to a part of the gas piston. When the bolt reaches the locking groove, the piston’s inertia forces the lifting lug to engage within the bolt, rotating this part of the bolt upwards towards the locking lug in the receiver. This, in turn, removes the obstruction that held the cross-piece, to which the firing pin mechanism is connected. Forced to move by the rotation of the rear part of the bolt, the cross-piece and firing pin continue to move forward another half-inch. The firing pin then enters its slot, and its tip strikes the primer of the cartridge in the chamber.
After the powder charge detonates and the bullet passes the gas port, located approximately 2/3 down the barrel, gas enters through the hole in the barrel and pushes on the face of the gas piston. The initial rearward movement of the piston retracts the firing pin tip from the spent primer, and after the cross-piece moves back approximately 13 mm, it releases two cams that hold the pivoting parts of the bolt connected to the locking lug. The bolt then assumes a horizontal position in the guides and begins to move rearward. The spring-loaded extractor removes the empty case from the chamber and continues to hold it close to the bolt face until the case reaches a slot in the receiver. At this time, the ejector, fixed to the receiver, strikes the case rim, rotates it, and ejects it downwards through the slot directly into the spent case bag. Under the action of the feed spring, the magazine presents another cartridge into the ready position, and the recoiling parts continue to move rearward, compressing the mainspring. The full recoil stroke ends when the moving parts contact a spring buffer, which not only absorbs excess energy but also accelerates the mechanism’s forward movement during the cycle’s repetition. If the trigger remains pressed, the reverse movement leads to the repetition of the cycle.
Key Specifications:
- Caliber: 7.7 mm (.303” British 7.7x56R)
- Action Type: Gas-operated
- Mass (unloaded): 9.5 kg
- Length: 1016 mm
- Barrel Length: 529 mm
- Rate of Fire: 950 – 1200 rounds/min
- Muzzle Velocity: 762 m/s
- Carriers (examples): Fairey “Battle”, Handley Page “Hampden”, Bristol “Blenheim”, Armstrong Whitworth “Whitley”, Fairey “Swordfish”, Fairey “Albacore”, Fairey “Barracuda”, Blackburn “Botha”.