The EM-2 was a prototype select fire rifle made just after WWII for trials England. It used an innovative .280 intermediate round, like the Soviet 7.62x39 M43 round used in the AK47 and the 7.92 short round used in the German MP44. The rifle passed the trials with flying colors and was set to be adopted, but at the last minute Winston Churchill vetoed the project in favor for the L1A1 FN FAL.
Real gun-

In Slab6

Fixed the sight, its much more accurate.
EDIT: Added firing sound from an SA80 and the reload sound from Blackops