New Weapon For The British Army: A 12 year old see Cadet demonstrates how easy the new Sterling sub-machine gun is to handle. A demonstration of the new Sterling sub-machine gun given at Daganham, near London. The weapon has now been adopted by the British Army and will be used instead of the Sten gun, and supplementary to the F.N. rifle. The Sterling - which weights 6 lbs - is capable of firing at the rate of 575 rounds per minute and can be used either as a fully of semi-automatic sub-machine gun, sighted for accurate shooting up to 200 yards. February 16, 1955.