At the end of the Second World War the British Army had two primary infantry machine guns: the Bren light machine gun and the Vickers medium machine gun. These weapons had proved their worth, the Bren was especially well liked and the venerable Vickers continued to be a reliable workhorse.
In the late 1940s, the British Army recognised the Soviet threat to Western Europe. In 1947, Field Marshal Bernard Montgomery, the newly appointed Chief of the Imperial General Staff wrote a paper outlining rearmament plans based on intelligence estimates of how quickly the Soviet Union was likely to be ready for another full-scale war. Montgomery believed that Britain had just 10 years to develop new weapons and begin rearmament before the Soviet Union had recovered enough to launch an invasion of Western Europe. As such the British Army felt that rearmament needed to be complete by the late 1950s.
A number of large budget programmes were launched while small arms projects were also undertaken. These included the Infantry Personal Weapon programme which sought to develop a new intermediate calibre infantry rifle – the IPW programme later yielded Stefan Janson’s EM-2, a bullpup chambered in .280, which was briefly adopted as the Rifle No.9. The FN FAL was later adopted due to changes in political circumstances – a long, fascinating story for another article. The companion to the IPW programme was the development of a Sustained Fire Machine Gun also chambered in .280. The TADEN, a belt-fed derivative of the Bren firing the new .280 round, was designed by Harold Turpin (‘T’), the Armament Design Establishment (‘AD’) and Enfield (‘EN’). With the abandonment of the IPW the TADEN was also abandoned but its design greatly influenced the later X11 developments.
Another major small arms programme at the time was the search for a new machine carbine (or submachine gun). This saw the testing of designs from Sterling, BSA and Madsen – with the Sterling finally adopted as the L2.
The other major small arms project was the programme to find a new section level machine gun. The German MG34 and MG42 had impressed the Allies during the war, so much so the US went as far as to clone it with the T24. After the abandonment of the EM-2 and TADEN machine gun the British issued a new specification for a lightweight sustained fire machine gun, chambered in the 7.62x51mm round recently adopted by NATO, in the mid-1950s.
The design team at the Royal Small Arms Factory at Enfield developed a belt-fed derivative of the Bren light machine gun. The X11 series of prototypes sought to convert the Bren’s proven design into a weapon capable of sustained fire. The X11 made a number of changes to the Bren included the addition of a detachable butt/grip/trigger assembly which could be swapped for a pair of spade grips and a paddle trigger for static sustained fire from a tripod. This resulted in the pistol grip being located much further back than the traditional Bren’s.
It appears that during the mid-1950s British military parlance described the General Purpose Machine Gun as a Sustained Fire Machine Gun (SFMG). From the available photographs it appears that the L4 and X11 use the same barrel with its distinct flash hider. The receivers of all the prototypes appear to be milled to attach the optical long range sight seen above.
The main drawback with the X11 was its feed mechanism. The feed slide was indexed by a rotating vertical feed shaft which was driven by the gas piston’s recoil. This created a considerable amount of friction within the action. It had the effect of causing failures to feed during adverse conditions testing and elevated firing tests. A series of four X11 prototypes were developed with Harold Turpin (co-designer of the STEN gun and later TADEN) working on the new gun. Each prototype appears to have a sightly different trigger configuration. The most interesting of these is a two-finger double-crescent trigger reminiscent of the MG-34’s – from the photographs it appears that the conventional selector lever, used in the X11E2, was replaced with a fire-selector system similar to the MG-34’s (upper crescent – semi-auto, lower crescent – full-auto). However, the trigger of the example of the X11E4 examined by Vic (serial number #11) was fully automatic only, despite its crescent shape.
Below are photographs of examples of the three types held at the Royal Armouries:
The X11 was tested against the M60, French AA-52, Swiss MG51, Danish Madsen-Saetter, German MG-3, and the Belgian FN MAG. The FN MAG, designated the X15E1 by the British, fared best in the trials with the X11 coming second due to its feeding issues. In January 1958, the British abandoned the X11 and moved to adopt the X15E1 general purpose machine gun, negotiating a license for its manufacture. The weapon was finally adopted as the L7A1 in 1961, with production at Enfield beginning in 1963. It seems that the Birmingham Small Arms Company were a latecomer to the competition having developed the another belt-fed Bren gun derivative known as the X16.
The Bren did continue in service after the switch to 7.62x51mm. In 1954, before beginning work on the X11, Enfield had developed the X10E1. Taking a Canadian manufactured 7.92x57mm Bren breech block and converting it to cycle the new round. The X10E1 was formally adopted as the L4. The L4 remained in service, alongside the L7, into the early 1990s. The L7 GPMG continues to be used by the British Army.
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The Bren Gun Saga, T. B. Dugelby (1999)