EM2

The Royal Small Arms EM2 rifle was an early experimental British assualt rifle.

In the immediate post-World War II era the British Army, like many other forces, started research into their own versions of the StG44. The army had planned to replace their .303 inch rimmed cartridge before WWI but were forced to keep it due to time and financial constraints for another 30 years. With these constraints removed, they developed a new .280 inch (7 mm) intermediate-power round, and set about developing a new rifle to fire it. At the same time Fabrique Nationale expressed considerable interest in the round, and started development of their own rifles based on 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 at Enfield started working on two generally similar designs known as the Experimental Models 1 and 2. Both were bullpup style weapons ie the magazine and chamber are placed behind the trigger and pistol grip, leading to a shorter overall design (by about 20%) and a better ratio between barrel length and weapon length. It used 20-round magazines with "stripper" reloads, included simple conical optical sights for fast shooting, and had a carrying handle built into the top. They could fire semi-automatic or fully automatic. The .280 round was accurate to about 800 yards (730 meters). The two differed primarily in details, but the EM2 was eventually selected as the better design (though some say it was mostly due to it looking less space age), and entered limited service in 1951 as Rifle, Automatic, Caliber .280, Number 9 Mark 1.

It was at this point that the US put forth its own designs for NATO standardization, using the .308 inch (7.62 mm) round in their M-14 rifle. Matters came to a head in 1951 in a shoot-off, with the US claiming the British round was underpowered, and the British claiming the US round was too powerful to be used in a full-auto mode. 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. The EM2 could not be easily adapted to the .308 round, so instead the British were forced to adopt a licensed version of the FN FAL from Fabrique Nationale, itself an adaptation of their own .280 rifle design re-chambered for the .308.