Family of Sten SMG’s showing top to bottom:
NZ Contract Sten MkII
Sten MkII with early stock
Radio Corp New Zealand Contract Sten Mk II & III hybrid
Sten Mk II disassembled
In 1940 Britain was in grave danger of invasion and every type of weapon was scarce. The only submachine- guns available were US Thompsons, and though, a hurried design effort had produced the Lanchester from the German MP 28 this was too expensive in factory effort to make in quantity. There was a desperate need for something simple and effective, and in January 1941 the Design Department of the Royal Small Arms Factory announced that they had found an, answer and had made prototypes. This was a much simplified Lanchester, coupled with some ideas from a captured MP 40; in particular the manufacturing processes of the MP 40 were accepted to the new weapon and stampings and components that could be subcontracted in their entirety were used to the full.
The gun was attractively light and compact and a limited endurance trial of 5000 rounds seemed to prove the soundness of the design. It was named the Sten, the letters being taken from the surnames of the two designers (Major R V Shepherd and Mr H J Turpin, who did most of the detailed work) and the location of the Enfield factory. The overriding requirement for the Sten was simplicity of manufacture and the use of easily available materials. The resulting gun must have horrified the traditional gun makers since it was crude in the extreme; but it worked, though the Mark I had a number of elaborations which soon proved to be of little or no use. There was a folding forehand grip, l conical flash-hider and some wooden furniture.
The basic mechanism set the pattern for the 3 million or so which followed. The blowback system of operation used a heavy bolt and a fairly strong return spring, a combination which gave a rate of fire of about 550 rds/min and ensured that the working parts were tolerant of dirt, dust, snow, mud and general neglect. The barrel was short clod was held in a tubular metal sleeve, and the body was another similar metal tube. The only machined parts were the bolt and barrel; everything else was stamped or pressed and all joins were by pinning or welding. It was quickly found that manufacture of most of the components could be contracted out to little machine shops and even to large garages around the country. These parts were all gathered in one of the main factories for fitting together, and to be mated with the barrels which held to be made on special machines. The first production models were turned out from BSA in the late summer of 1941 and from then on by both BSA in Birmingham and Enfield in quantity.
The Mark I was soon replaced by the Mark II which was the most famous of the series. It was much simplified, with all unnecessary frills removed. The stock was a single tube with l flat plate on the end for the shoulder, and the woodwork and forehand grip disappeared. The barrel was held in by a screwed jacket and was easily removed. The magazine housing could be rotated to lie in the same plane, as the trigger mechanism. The stock was only held by a spring stud, and when taken down to its component parts the Mark II could be carried very easily. It became a favourite of the French Resistance and other underground movements in Europe and in the end more than 2 million were made, a few of which still exist today.
The Mark III was introduced by Lines Brothers, l firm of toy makers, who had a large contract. They made yet more simplifications in the manufacture, building a gun which had a fixed barrel and the body and jacket all in one. It was probably the best version of the Sten, but did not appear in large numbers. In line with the then popular policy of making folding weapons for airborne troops, the Mark IV, IVA and IVB were tried. All followed the same general pattern of turning the gun into a form of automatic pistol with the same mechanism and magazine. This did not work satisfactorily and none of these small versions was ever put into production. A folding or telescoping stock might have achieved a worthwhile result, but for some reason this was never tried.
The Mark II was fitted with a silenced barrel in 1943 and became the first silenced submachine-gun to be accepted into service. Quite large numbers were made and it was a most effective night weapon.
Despite its advantages the Sten was never very popular with the British Army who knew it by a number of uncomplimentary names. The magazine gave some trouble with jams; though it was a perfect copy of that used in the MP 40, it was no comfort to the users to know that the Germans suffered the same sort of jams themselves. The magazine could be neither changed nor improved, so in an effort to convince the troops that a better weapon had been built the Mark V Sten was brought out in 1944. Various small manufacturing improvements were made, and the gun was dressed up with a wooden butt clod pistol grip. The Mark V was a good gun, and had it not been saddled with the same magazine it might have been the best submachine-gun of the whole war. It remained in British Army service until the early 1960s. During the Second World War the Sten was used by all the Allies, and was dropped to underground movements, all over the world; it was used on every battlefront and was copied by enemies.
(Mark I) Calibre: 9 mm (0.354 in) Ammunition: 9-mm Parabellum Weight: 3.26 kg (7 Ib 3 oz) unloaded Length: 895 mm (35.2 in) Barrel length: 196 mm (7.7 in) Magazine: 32-round detachable box Rate of fire: 550 rds/min (cyclic) Muzzle velocity: 381 m/sec (1250 ft/sec)
(Mark II) Calibre: 9 mm (0.354 in) Ammunition: 9-mm Parabellum Weight: 2.95 kg (6 Ib 8 oz) unloaded Length: 762 mm (30 in) Barrel length: 196 mm (7.7 in) Magazine: 32-round detachable box Rate of fire: 550 rds/min (cyclic) Muzzle velocity: 381 m/sec (1250 ft/sec)
(Mark II, silenced) Calibre: 9 mm (0.354 in) Ammunition: 9-mm Parabellum Weight: 3.52 kg (7 Ib 12 oz) unloaded Length: 907 mm (35.7 in) Barrel length: 89 mm (3.5 in) Magazine: 32- round detachable box Rate of fire: 450 rds/min (cyclic) Muzzle velocity: 305 m/sec (1000 ft/sec)
(Mark III) Calibre: 9 mm (0.354 in) Ammunition: 9-mm Parabellum Weight: 3.18 kg (7 Ib) unloaded Length: 762 mm (30 in) Barrel length: 196 mm (7.7 in) Magazine: 32-round detachable box Rate of fire: 550 rds/min (cyclic) Muzzle velocity: 381 m/sec (1250 ft/sec)
(Mark V) Calibre: 9 mm (0.354 in) Ammunition: 9-mm Parabellum Weight: 3.86 kg (8 Ib 8 oz) unloaded Length: 762 mm (30 in) Barrel length: 196 mm (7.7 in) Magazine: 32-round detachable box Rate of fire: 600 rds/min (cyclic) Muzzle velocity: 381 m/sec (1250 ft/sec)