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The Bren (Brno, Enfield, officially cased BREN) was a British light machine gun that was produced by RSAF Enfield. Based on the Czech ZB Vz.27, the Bren saw extensive use by the British Army during World War II, during which it earned a favorable reputation for its reliability and accuracy.


After World War I, the British Army wanted to replace the Lewis gun with a lighter and more reliable weapon. Initially in 1922, the BAR was selected, but its adoption was cancelled shortly afterward. A variety of international submissions were tested by the Small Arms Committee afterward, and in the late 1920s the British military attaché in Prague observed a demonstration of the ZB vz. 26 light machine gun. Impressed by its performance, they recommended it to the Small Arms Committee, who ordered a single trial model from Brno at the total cost of £262, making it one of the most expensive weapons purchased by the SAC.

The gun that Brno ultimately sent to Britain was not, in fact, a Vz.26 - instead a Vz.27 was delivered, and on the 29th of October 1930 it was submitted into military trials against the Madsen, Vickers-Berthier, BAR, Darne (which was not tried), and KE7. The Zb.27 was one of the only guns trialed that was not in .303 caliber, but was instead tested in 7.92×57mm. Of the guns tested, the Zb.27 got by far the best report and the Chief Inspector of Small Arms noted of the gun in his report: "Functioning - excellent throughout. I doubt whether any other gun has ever passed through so many tests with us, giving so little trouble". Further trials took place in April 1931 with a Zb.30 chambered in .303, and in June the Zb.30 was entered into comparative tests at Hythe against the Vickers-Berthier and Darne. Once again the Brno gun got an outstanding report, with only two defects reported - the gun was susceptible to fouling when loaded with cordite ammunition, owing to the location of the gas port; and also some ejection issues due to ejection port's design around the 7.92mm cartridge rather than .303. The weapon was sent back to Brno with this feedback, and was redesigned by Karel Staller and Václav Holek to fit the British specifications.

When it was sent back to Britain, Mr. Holek accompanied it to oversee the tests personally. There were only 90 jams observed in the 15,000 rounds fired and there was very little in the way of criticism from the SAC. The only concern that was raised was the magazine capacity; the British Army wanted a 30-round magazine in place of the Zb.30's 20 rounds. In 1933 the British Director of Munitions went with Mr. Holek to the Brno factory to observe the design process of the gun and suggested improvements to the gas piston buffer. With these changes incorporated, the gun was submitted to tests at Enfield as the ZGB-32. Feedback from these tests yielded a further 25 improvements to the design, which was subsequently resubmitted as the ZGB-33 and trialed on the 29th of January 1934, with over 140,000 rounds being fired from the gun before any major failures.

In August, the new ZGB-34 was tried against the Vickers-Berthier. The trials were extremely thorough, with both guns being subjected to 50,000-round endurance tests, and ultimately the ZGB was seen to be more reliable. The decision was made in 1937 to adopt the gun, officially replacing both the Vickers and the Lewis gun. The decision caused a slight upset among some British officers, who felt that the Vickers-Berthier gun should be adopted, in accordance with the decisions made by the British Indian Army. RSAF Enfield were allocated the production rights to the ZGB; they had in fact already been in negotiations with Brno since 1934 and had already set up tooling for the gun, as its adoption was anticipated ahead of time. At Enfield, the ZGB was renamed the Bren after Brno and Enfield. The first model was made in September 1937. By the Summer of 1938, the Bren was being produced at a rate of 300 guns a week.

With the outbreak of World War II in September 1939, production was scaled up significantly, with a further 100 guns being produced every week. By June 1940 there were about 30,000 Bren guns in the British Army's inventory, with most of these guns being lost during the British evacuation from Dunkirk. The British units stationed at home had only 2,300 Bren guns and consequently Enfield had to practically re-arm them from scratch.

Over the time of World War 2, there were several modifications.

Mk.I (M) was a name applied to Canadian-produced Mk.I guns. These lacked the dovetail mount and screw attachment for a dial sight, the folding metal buttstrap, and the rear grip, and had a slightly different flash hider.

The Mk.II changed the rear sight from a drum-adjusted aperture to a simple flip-up ladder sight, changed the bipod to a fixed-height one, simplified the carry handle, and had a sheet metal buttplate instead of a buffer. The flash hider, gas regulator, and front sight, which were all a single stainless steel unit on the Mk.I, were separated into three different parts, with only the regulator now being made from stainless steel.

The Mk.III was a simplified version of the Mk.I with a shorter barrel, while the Mk.IV was a short Mk.II. Both versions also had additional milling performed to reduce weight to the absolute minimum required to handle the Mk.VIII .303 cartridge. They were initially intended for paratroop use.

The Taden Gun was a belt-fed Bren variant produced in 1951 chambered for the .280 British intermediate rounds, but was axed alongside the Enfield EM2 when Britain was forced to abandon the .280 round after joining NATO.

L4 was a postwar series converted to fire the standard 7.62mm NATO round after Britain joined NATO in 1954. The most notable change is the use of straight 20 or 30-round inch-pattern FN FAL magazines, and the use of a slotted flash hider. Variants include the L4A1 (modified Mk.3), L4A2, L4A3 (Royal Navy model), L4A4, L4A5 (developmental model - never built) and the L4A6.

There was also a Chinese variant converted to fire the 8mm Mauser and 7.62 Russian rounds.

Bren had stayed in service until 1991 where it saw service during Gulf War 1. Though officially, Bren is no longer in service, British Army and Navy still have a substantial number of L4A4 and L4A6 in stock. Additionally, Bren guns are still in use in countries which imported British weaponry, like India where it is manufactured as the Machine Gun 1B.

Technically, Bren is gas-operated, air-cooled, magazine-fed machinegun. Magazines fit 30 cartridges, and are inserted from top - one of the trademark characteristics of the Bren. Due to that, sights are offset to the left. Another unusual feature is that barrel and bolt assembly can roll back within the receiver, thus dampening recoil. Barrel is quick-changeable, and most of Bren guns are shipped with replacement barrel. (L4A4, L4A5 and L4A6 modifications have chromed barrel and chamber, and thus, were shipped with single barrel.) All Bren guns are fitted with bipods.


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