The Sten was a family of british 9mm submachinegun used widely by British army during Second World War and Korean War.
he official designation "Carbine, Machine, Sten" should not be confused with the common understanding of carbine; the Sten was a typical, almost stereotypical submachine gun while the term carbine is used to refer to short, light rifles. The "Carbine, Machine" element of the designation resulted from the British term for a submachine gun - "Machine Carbine" - in the early part of the Second World War.

HISORY OF THE "STEN"
The Sten emerged while Britain was engaged in the Battle of Britain facing invasion by Germany. The army was forced to replace weapons lost during the evacuation from dunkirk while expanding at the same time.Prior to 1941 and even later the British were purchasing all the Thompson submachine gun they could from the United State but this did not begin to meet demand. The American entry into the war at the end of 1941 placed an even bigger demand on the facilities making Thompsons. In order to rapidly equip a sufficient fighting force to counter the Axis threat, the Royal Small Arms Factory, was commissioned to produce an alternative.

The Sten required a minimum amount of machining and manufacturing effort by using simple stamped metal components and minor welding. Much of the production could be performed by small workshops and the firearms assembled at the Enfield site. Over the period of manufacture the Sten design was further simplified: the most basic model, the Mark III, could be produced from five man-hours work. Some of the cheapest versions were made from only 47 different parts. It was distinctive for its bare appearance (just a pipe with a metal loop for a stock), and its horizontal magazine. The Mark I was a more finely finished weapon with a wooden foregrip and handle; later versions were generally more spartan, although the final version, the Mark V, which was produced after the threat of invasion had died down, was produced to a notably higher standard.

SPEC

The sten has weight of 3.2 kg,length of 760mm and has 195mm of barrel length.STEN used the cartridge of 9x19 parabellum.use 2 action that is blowback-operated and open-bolt action.Muzzle velocity of 365 m/s.The effective range was only 60m,using 32-rd detachable box magazine.