EM - 2 rifle The EM - 2 , Also known as Rifle No . 9 Mk1 or " Janson rifle " , was an experimental British assault rifle . It was briefly adopted by British forces in 1951 , but the decision was overturned very shortly thereafter by Winston Churchill ' s incoming government in an effort to secure NATO standardisation of small arms and ammunition in the face of American intransigence . An innovative weapon with the compact bullpup layout and an optical sight , it used one of the early intermediate cartridges ( a concept introduced by the Germans with the 7 . 92x33mm Kurz ) as a result of combat experience and German advances in weapons design during World War II . It used the experimental , intermediate powered , but highly efficient . 280 British round , which was designed to replace the venerable . 303 round and Lee - Enfield rifle variants which had served since before the turn of the 20th century . The United States claimed the . 280 British round was too weak for use in rifles and machine guns , and instead favored the much more powerful 7 . 62x51mm round . As the EM - 2 could not be easily adapted to the longer and more powerful round , it faded from use . However , the bullpup layout for a British service rifle was finally adopted some years later in form of the SA80 assault rifle , the EM - 2 ' s spiritual successor , which remains in service today . Background . In the immediate post - World War II era , the British Army , like many other forces , started research into their own assault rifle . The British Army had originally planned to replace their . 303 inch rimmed cartridge before World War I , but were forced to keep it for another 30 years due to time and financial constraints . With these constraints removed , they developed a new . intermediate - power round , and set about developing a new rifle to fire it , as well as considering a machine gun using the same round , the Taden gun . At the same time Fabrique Nationale expressed considerable interest in the round , and started development of their own rifles based upon it . The Canadian Army also expressed interest in the new round , both to maintain commonality with the British and to modernize their forces . The Royal Small Arms Factory ( RSAF ) at Enfield started working on four designs , of which two generally similar designs known as the EM - 1 ( designed by Stanley Thorpe ) and the EM - 2 ( the " EM " standing for " Experimental Model " ) came to the fore . The EM - 3 ( designed by Major Eric Hall ) and EM - 4 ( designed by Dennis Burney ) did not proceed beyond the drawing board . The nomenclature was made official on January 6 , 1948 . Both were unofficially named after the lead designers in each team and were known as the Thorpe rifle and the Janson rifle respectively ( Stefan Kenneth Janson was an assumed name of the Polish firearm designer Captain Kazimierz Januszewski ) . Both were Bullpup style weapons ; the magazine and chamber are placed behind the trigger and pistol grip , leading to a shorter overall length ( by about 20 % ) and a better ratio between barrel length and weapon length ( the overall length of the EM - 2 is 9 . 5 inches less than the U . S . M14 , but its barrel is 2 . 5 inches longer ) . Both EM - 1 and EM - 2 used 20 - round magazines with " stripper " reloads , included simple conical optical sights for fast aiming , and had a carrying handle built into the top . They could fire semi - automatic or fully automatic . The . 280 round was accurate to about . The two designs were very similar looking , but were internally very different in design and construction , with no parts in common other than the sights . The EM - 1 used steel plate pressings for simpler manufacture , and was slightly heavier . A fifth design was commissioned from the BSA company , who built prototypes of a more conventional rifle using the same 7mm round , the BSA 28P . The EM - 2 was eventually selected as the better design , and was adopted as the British Army ' s new rifle on April 25 , 1951 as the " Rifle , Automatic , Calibre . 280 , Number 9 " , the designation by which it had been known in the War Office since the American weapons tests of 1950 . In common with other 20th century British designs such as the P14 and SA80 , the EM - 2 was designed to achieve a high degree of accuracy due to the tradition of British Army emphasis on marksmanship . Though not adopted , the British Herald Miniatures toy soldier company designed its modern British Infantry figures using the weapon . NATO standardisation . With the creation of NATO in 1949 , there was a clear preference that NATO forces would have commonality of weapons and ammunition , so weapons designs had to meet with the approval of more than one government , and it was hoped , would be adopted by the organisation as a whole . It was at this point that the US put forth its own designs for NATO standardisation , using the 7 . 62x51mm round in their prototype T25 and T44 rifles . Matters came to a head in 1951 in a shoot - off conducted at the Aberdeen Proving Grounds , with the US claiming the British round was underpowered , and the British claiming the US round was too powerful to be used in a rifle in full - automatic mode . At the same trials the Belgian . 280 FN FAL was also tested . A series of lengthy debates followed , which were finally settled in an unlikely fashion when Canada stated they would use the British . 280 round , but only if the US did as well . It was clear this would never happen . Winston Churchill felt a NATO standard was more important than any qualities of the weapon itself and overturned the decision by the previous Labour Minister of Defence , Manny Shinwell , who had already announced an intention to move to the . 280 and the EM - 2 . During this time , prototype EM - 2s were built in several different calibres . Chambons built two for the 7x49mm " Second Optimum " cartridge and another two for the 7 . 62x51mm . One of the Chambon prototypes was even rebuilt for the US . 30 - 06 cartridge . RSAF - Enfield and BSA built 15 and 10 prototypes for the 7 . 62x51mm , respectively . Canadian Arsenals Limited also built 10 rifles for the 7x51mm " Compromise " cartridge . It was clear the EM - 2 could not be easily adapted to the powerful 7 . 62x51mm round , so the only realistic alternative was to adopt a licensed version of the FN FAL from Fabrique Nationale . The FAL was itself a re - designed version of FN ' s own design for an intermediate cartridge rifle using the . 280 round ( first protoypes had used the 7 . 92x33mm Kurz German round from the MP44 ) . However , the FAL was more easily adaptable to handle the more powerful , longer round . It grew in weight and length as a consequence . Churchill had hoped that with the British Commonwealth and other NATO countries adopting the FN FAL , the US Army would do so as well . In the end , the US adopted the T44 as the M14 , which had won US trials against the more radical T25 experimental weapon . In time , the British position on intermediate cartridges was vindicated . The 7 . 62x51mm was too powerful to be controllable in automatic fire and smaller cartridges were proven to be necessary for that use . Due to its experience in Vietnam in the mid - 1960s , the US adopted the AR - 15 as the M16 . Chambered for the 5 . 56x45mm intermediate cartridge , the M16 displaced the M14 which had been adopted little more than a decade earlier . Some years afterwards , NATO also agreed to move to a smaller round more suitable for full - automatic fire and lighter weapons , ultimately adopting the 5 . 56x45mm . Prior to committing to the 5 . 56mm , the British Army conducted additional intermediate cartridge research . Around 1970 , a pair of the original . 280 EM - 2 were re - barrelled for an experimental 6 . 25x43mm cartridge . However , the revival of the EM - 2 was short - lived as the 6 . 25mm was dropped for an even smaller 4 . 85mm cartridge in a completely new rifle , the L64 / 65 which evolved into the 5 . 56mm SA80 currently used by the British Army . In spite of having a similar appearance due to its bullpup layout , the SA80 is not mechanically related to the EM - 2 ; rather it is essentially a bullpup adaptation of the AR - 18 / SAR - 87 . However , the idea of an " Infantry Personal Weapon " , which led to the design of the EM - 2 , was reflected in the SA80 system .