The BREN Light Machine Gun was the standard light machine gun of the British Army and Commonwealth forces throughout World War 2 and beyond. The type's existence was actually owed to the 1920's-era Czech ZB vz/26 Light Machine Gun brought to the British Army's attention prior to adoption of other types during a long-lasting, years-long search. The simple-yey-excellent ZB vz/26 was adopted by the Czech Army in 1924 with production out of the storied Brno facility. Chambered for the 7.9mm rimless cartridge, it operated from a top-fed, straight detachable box magazine through a gas-operated action featuring a tilting breechblock. The weapon was heavily adopted elsewhere (including Nazi Germany as the MG 26(t)) and saw extensive service in the Chinese Civil War (1927-1937, 1946-1950), World War 2 (1939-1945), the Malayan Emergency (1948-1960), the Korean War (1950-1953), the Suez Crisis (1956), the Congo Crisis (1960-1965), the Rhodesian Bush War (1964-1979), The Northern Ireland "Troubles" (1966-1998) and the Falklands War (1982).
Prior to World War 2, the British Army sought to find a viable and improved replacement for their existing Lewis Light Machine Gun line which proved a limited light machine gun design at best. A visit to Czechoslovakia alerted authorities to a locally-designed, well-rounded system in the ZB vz/26. With examples delivered to Britain for further testing in 1930, several other competing designs were entertained well into 1934. The ZB vz/26 evolved into the vz/27 and this begat the vz/30, vz/32 and vz/33 marks in time. All preceding marks up to the vz/30 were modified to fire the original 7.92mm Mauser cartridge which was of little value to the British need. It was the vz/30 that adopted the .303 British cartridge as the "ZGB vz/30" prototype of 1930 and underwent trials from 1931 to 1932. The following ZGB vz/33 development of 1933 became the official basis for the finalized British design. It was soon settled to adopt the Czech system for the Army with the British-centric changes to suit requirements. Design work continued into 1935, affording the design the official designation of "BREN" which paid homage to the weapon's true origin (BR = "Brno") and its place of main manufacture (EN = "Enfield Lock" through the Royal Small Arms Factory).
The primary (and most major) change to the Czech design was in the chambering - the Czech version utilized the German 7.92mm Mauser rimless rifle cartridge. For the sake of logistics and familiarity, the British instead opted for their .303 British rimmed rifle cartridge which was already in widespread circulation. This then forced changes to the Czech design's internals and a new curved magazine was developed to house the rimmed cartridges (giving the BREN its very defined and highly recognizable profile). The end result was largely faithful to the original Czech offering with its gas-operated, tilting bolt repeat-fire action retained. The overall design was highly linear in its general form with the rectangular receiver capped at one end by a solid shoulder buttstock and at the other end by the usual barrel and gas cylinder arrangement. The gas cylinder was fitted under the barrel in a traditional way and tapped expelled high pressure gas from exiting rounds for use in each subsequent round by converting the gas into required pressure to work the internal action. The weapon featured a standalone pistol grip with integrated trigger group slung under the rear portion of the receiver. A carrying handle was affixed to the barrel roughly at the midway point of the design. The barrel was capped by a conical flash hider and a folding bipod was fitted at the tip of the gas cylinder. The charging handle was set to the right side of the receiver and the new curved magazines were inserted through a top-mounted gate. Spent shell casings were ejected cleanly through the bottom of the receiver.
Production was assigned to the fabled Royal Small Arms Factory at Enfield Lock and set to begin in 1937. First deliveries began to reach frontline units in 1938. As British and Commonwealth involvement ramped up, so too did production of the BREN and eventually involved Canadian (Inglis and Long Branch), Australian (Lithgow) and Indian (Ishapore) factories. With the Chinese caught in its own bitter war against the Empire of Japan in Asia, BREN guns were also competed in their original 7.92mm Mauser chambering and sent overseas in support of Nationalist Chinese forces.
In practice, the BREN gun met nearly all expectations as a reliable, combat-friendly portable weapons system. Its sheer simplicity in design allowed for quick repair and maintenance in-the-field where gunners could quickly assemble and field-strip the weapon in minutes. The action also proved highly sound so as to produce a minimum number of stoppages. The type's overall weight - approximately 22.5lbs - made the BREN very portable in long marches and when relocating the gun to more advantageous positions. It featured a sound effective target range of 600 yards and a maximum area range out to 1,850 yards with a firing rate of 500 to 520 rounds per minute - the seemingly low rate-of-fire accounting for more effective cooling of the barrel between bursts, and thusly lowering the chance of a fractured barrel being encountered. An overheated barrel could also very quickly be addressed by the two-man crew in minutes. The .303 British cartridge gave good penetration value at range with its 2,400 feet per second muzzle velocity. Sighting was through iron arrangements standardized on the design from the beginning. If the BREN held any limitations, it was in its 30-round magazine which allowed for limited bursts of firing before reloading was required. However, as a light machine gun, use of magazines made for a highly portable weapon not requiring belted ammunition which could misfeed without proper attention. An operator not use to the downward ejection of casings could also be caught by surprise. Nevertheless, BREN machine gunners enjoyed their weapon and considered it a very accurate ranged system. A typical issue in British ranks was one gun per section with a crew of two assigned to each weapon - ammunition dispersed across the section.
BREN use was not only limited to its defined light machine gun, squad-level role. Several mounting types soon appeared which broadened the tactical role of the weapon considerably. Specialized tall tripod mountings allowed for the weapon to be used as a low-level anti-aircraft defensive system (complete with an empty casings soft bag) to help defend airfields and the like. The BREN was also a standard fixture across many British and Commonwealth military vehicles of the war when fitted on trainable mounts, able to engage cleanly around the vehicle and over it. A heavy duty tripod (weighing some 26.5lbs) was developed with applicable sighting optics and this made the BREN an effective defensive system when used in a fixed position while protecting vital areas and camps.