Sten submachine gun

The Sten (or Sten gun) was a family of British 9 mm submachine guns used extensively by British and Commonwealth forces throughout World War II and the Korean War. They were notable for having a simple design and very low production cost.

STEN is an acronym, cited as derived from the names of the weapon's chief designers, Major Reginald Shepherd and Harold Turpin, and EN for Enfield. Over 4 million Stens in various versions were made in the 1940s.

The 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 was due to the British term for a submachine gun being a "Machine Carbine" in the earlier parts of the Second World War.

History

In January 1941 the design department of the Royal Small Arms factory at Enfield, Middlesex, produced the prototype of what was to become the best-known Sub-Machine Gun of World War II. The Sten introduced an entirely new concept into the manufacture of SMGs as previously all such guns had been manufactured using traditional gunsmith’s methods (often with the body and trigger housing being machined from the solid); an expensive and time-consuming operation. The Sten, however, would utilize cheap steel pressings, low grade metal, and had no fancy refinements at all. The finish was rough, with no wood being used in the stock or hand-grips and all other components kept to the basic minimum. Even so the first model, the Mark I, was still considered to be far too complicated and was quickly replaced by the Mark II, the production of which would ultimately result in over two million guns being produced by the ending of hostilities in 1945.

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 guns they could from the United States of America, 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, Enfield, was commissioned to produce a significantly cheaper alternative.

The credited designers were Major R. V. Shepherd, OBE, Inspector of Armaments in the Ministry of Supply Design Department at The Royal Arsenal, Woolwich, (later Assistant Chief Superintendent at the Armaments Design Department) and Mr. Harold John Turpin, Senior Draughtsman of the Design Department of the Royal Small Arms Factory (RSAF) Enfield. Shepherd had been recalled to service after having retired and spending some time at BSA.

The Sten required a minimum amount of machining and manufacturing effort by using simple pressed 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; some later versions were not quite as spartan.

The Sten was slowly withdrawn from British service in the 1960s, and was replaced by the Sterling SMG. The other Commonwealth nations made or adopted their own replacements. The Sten was used extensively by Jewish partisans during the Israeli War of Independence.

Design

The Sten gun was chambered for the 9x19mm Parabellum pistol cartridge. The Sten was small and could be stripped down into a set of easily concealed components and was therefore particularly suited to partisan operations on the continent or in Special Operations Executive operations in German-occupied France. Guerrilla fighters in Europe became adept at repairing, modifying and eventually scratch-building clones of the Sten (over 2,000 Stens and about 500 of similar Blyskawica SMGs were manufactured in occupied Poland).

The Sten was a simple, open bolt, blowback operated, selective-fire firearm. Single shots and full automatic fire were selected by a cross-bolt type push-button located in front and above the trigger. The tubular receiver and the barrel sleeve were made from rolled steel. It was fed from a box magazine attached to the housing on the left side of the gun. Various stocks were used with different models, all steel skeleton and tubular stocks to wooden stocks and pistol grips. The sights were fixed, consisting of a rear peep and front blade, zeroed to a nominal 100 yards.

Stoppages could occur due to the magazine, a direct copy of the one used in the German Erma MP38/MP40. The magazine had two columns of tapered 9 mm cartridges arranged side-by-side in a zig-zag manner. To allow the magazine box to be straight, the front of the magazine was tapered to complement the taper of the cartridges. While other staggered magazines fed from both the left and right positions, the Sten magazine required the cartridges to gradually merge at the top of the magazine to form a single column. Any dirt or foreign matter in this taper area could cause feed malfunctions. Additionally, the walls of the magazine lip had to endure the full stresses of the rounds being pushed in by the spring. This could result in deformation of the magazine lips, resulting in misfeeds. To facilitate easier loading to the great resistance when attempting to push the cartridges down to insert the next one, a magazine filler tool was developed and formed part of the weapon's kit. Modern 9 mm magazines, such as those used by the Sterling SMG, are curved and feed both sides to avoid this problem.

A well-maintained Sten gun is a devastating close-range weapon. If a Sten does jam with the bolt forward, standard practice to clear it is as follows: tilt the Sten to the right to allow gravity to pull jammed rounds out through the cartridge ejection port, whilst recocking the weapon. Then the weapon is fired again as normal. An easy action to memorise even under stress.

The slot on the side of the body where the cocking knob ran was a target of criticism, as the long opening could allow foreign objects to enter. On the other hand, a beneficial side-effect of the Sten's minimalist design was that it would fire without any lubrication. This was useful in desert environments where oil attracts and retains dust.

The Sten underwent various design improvements over the course of the war. For example, the Mark 4 cocking handle and corresponding hole drilled in the receiver were created in order to prevent an accidental discharge issue. However, most changes to the production process were more subtle, designed to give greater ease of manufacture and increased reliability. Sten guns of late 1942 and beyond were highly effective weapons. Such was the ease of manufacture that the Germans also produced a version of the Sten, the MP 3008, late in the war.

Variants

Sten guns were produced in several basic marks, (though the MKI saw limited service, and the MKIV was never issued) and nearly half of the total produced were of the Mark II. Approximately 4.5 million Stens were produced during the war.

Mark I

The first ever Mk I Sten gun (number 'T-40/1' indicating its originator Harold Turpin, the year 1940 and the serial number #1) was handmade by Turpin at the Philips Radio works at Perivale, Middlesex during December 1940/January 1941. This particular weapon is held by the historical weapons collection of the British Army's Infantry and Small Arms School Corps in Warminster, Wiltshire.

The first model had a conical flash hider and fine finish. It had a wooden foregrip and forward handle (sometimes this was made of steel), as well for a section of the stock. The stock was a small tube outline, rather like the Mark II Canadian. One unique feature was that the front pistol grip could be rotated forward to make the firearm easier to stow. The barrel sleeve extended all the way to the end, where it had conical flash hider. Along the top of the tube surrounding the barrel was a line of small holes and its sights were configured somewhat differently. About 100,000 were made before production switched to the Mark II. Sten Mk I's in German possession were designated MP.748(e).

Mark I*

This was the first simplification of the Mk I. The foregrip, the wooden furniture and the flash hider were deleted for production expediency.

Mark II

The Sten Mark II was possibly the most versatile of the several Sten models as well as the most prolific, at two million units produced. It was a much rougher weapon than the Mk I. The simple blow back bolt was not only simple but was a highly effective system for automatic fire. The Gun itself had a singular tube skeleton butt, a removable barrel and fixed sights. The flash eliminator and hand guard (grip) of the Mk I were eliminated. Other changes included adding the removable barrel which projects 3 inches beyond the barrel sleeve and the magazine housing rotates to form cover for ejection opening. The barrel sleeve was shorter and rather than have small holes on the top, it had three sets of three holes equally spaced on the shroud. Sten Mk II's in German possession were designated MP.749(e). Some MkIIs were fitted with a wooden stock.

It would be employed in every theatre of war and was particularly favoured by the French Resistance Fighters because it could be easily dismantled and hidden away in a shopping basket or small suitcase. Another useful advantage for the Resistance movements was that the Sten had been designed to fire standard German 9mm ammunition, thus allowing captured enemy rounds to be employed without problem.

Regular Mark II:

  • Overall Length: 762 mm (30 in)
  • Barrel Length: 197 mm (7.8 in)
  • Weight: 3.2 kg (7.1 lb)

Mark II (Canadian)

During World War II a version of the Sten gun was produced at the Long Branch Arsenal in Long Branch, Ontario now part of Toronto, Ontario. This was very similar to the regular Mark II, with a different stock slightly improved quality. It was first used in combat in the Dieppe Raid in 1942.

Mark III

This simple design was the next most commonly produced after the Mark II. It was a simplification of the Mk I made both in Canada and the UK. Lines Bros Ltd was the largest manufacturer. The biggest difference from the Mark II was the unification of the receiver, ejection port, and barrel shroud that now extended farther up the barrel. The barrel was fixed and the body was welded shut along the centre of the top. Captured Sten Mk IIIs in German possession were designated MP.750(e).

Mark IV

The Mark IV was a smaller version which did not progress beyond the prototype stage. It was near pistol-sized and it had a different configuration with a conical flash hider, a rear pistol grip, a very light stock and a much shorter barrel.

Mark V

Changes included a wooden grip, a wooden fore grip, a wooden stock, and a bayonet mount. The Sten bandolier issued to paratroopers held 7 full magazines.

Mark VI

  • Overall Length: 908 mm (35.7 in)
  • Barrel Length: 198 mm (7.8 in)
  • Weight: 4.5 kg (9.9 lb)

Suppressed models

Mark IIS and Mark VIS models (sometimes recorded as 6(s)) were produced which incorporated an integral supressor. This would heat up rapidly when fired and a canvas cover was laced around for some protection. The Mark 6 had a lower muzzle velocity than the others; 305 m/s (1,001 ft/s) and was also the heaviest regular version due to the added weight of the specially designed silencer, as well as using a wooden pistol grip and wooden stock. Sten Mk IIS's in German possession were designated MP.751(e).

The suppressed models were produced at the request of the Special Operations Executive (SOE) for use by their teams in occupied Europe. Starting with the Mk. IIS in 1943.

Foreign built copies and derivatives

Norwegian Sten
In German-occupied Norway the resistance, under leadership of Bror With, created a large number of Sten guns from scratch, mainly to arm members of the underground army Milorg. The same was done to some extent in Denmark.

Polish Sten
See the main article Blyskawica submachine gun

The Polish resistance was provided with numerous Stens of various models by the SOE and the Cichociemni. Between 1942 and 1944, approximately 11,000 Sten Mk IIs were delivered to the Armia Krajowa. Due to the simplicity of design, local production of Polish variants of Sten was started in at least 23 underground workshops in Poland. Some of them produced copies of Mark IIs, while others produced the so-called Polski Sten. The Polski Sten made in Warsaw under command of Ryszard Bialostocki were built from a number of legal elements made in official factories or acquired through other means. The main body of the machine pistol was made from hydraulic cylinders produced for hospital equipment. All the pistols were marked in English to disguise their origin and the production facilities. A modernized version of the Sten was produced in Poland under the name Blyskawica.

Gerät Potsdam
In late 1944, the Mauser works in Germany started manufacturing a series of copies of British Mk II Sten for diversion and sabotage purposes. The series was nicknamed the Gerät Potsdam and approximately 28,000 weapons were made.

MP 3008
The Germans too were greatly impressed by the simplicity of the Sten, paying it the supreme compliment of copying the design. In early 1945, Germany was seeking a cheap machine pistol for the Volkssturm (German Home Guard) to be used for guerrilla operations against the conquering Russians. For that purpose a modified Sten was designed by Mauser and named the MP 3008. The main difference was the magazine attached below the weapon. Altogether, roughly 10,000 pieces were produced before the end of World War II.

** Neumünster Device**
The Neumünster Device was manufactured prior to the MP3008 under great secrecy by Mauser Waffenfabrik. The Neumünster device was an almost perfect copy of the British Sten, even down to its British proof marks. The reason for manufacturing the Neumünster Device is unknown but they were manufactured at great expense. Each Neumünster Device cost eight times as much as a Mauser Model 98K rifle.

Austen MK I
The Mark I Austen (from "Australian Sten") was a 9 millimeter Australian submachine gun derived from the British Sten gun developed during the Second World War by the Lithgow Small Arms Factory. Approximately 45,000 Austens were produced from 1942 to 1944. They remained in service as a standard weapon of the Australian Army until 1966.

Sputter Gun

An American invention, the Sputter Gun was designed to circumvent the law that defined a machine gun as something that fired multiple rounds with one pull of the trigger. The Sputter Gun had no trigger, but fired continuously after loading and the pulling back of its bolt, firing until it ran out of ammunition. The gun was very short lived as the ATF quickly reclassified it.

Service

The Sten, especially the Mark II, tended to attract affection and loathing in equal measure. Its peculiar appearance when compared to other firearms of the era, combined with reportedly questionable reliability and durability made it unpopular with many front-line troops. It gained nicknames such as "Plumber's Nightmare", "Plumber's Abortion", "Stench Gun" or "Woolworth's Gun". The Sten's attractions were ease of manufacture and availability in the massive numbers required during a major conflict.

There are numerous accounts of the Sten's unreliability, some of them true, some exaggerated and some which are apocryphal. France manufactured Sten copies postwar into the early 1950s, which they would have avoided if Sten reliability and durability were truly as abysmal as some claims assert.

Stens were air-dropped in quantity to resistance fighters and partisans throughout occupied Europe. Due to their slim profile and ease of disassembly, they were good for concealment and guerrilla warfare.

A famous ambush involving a Sten - the assassination of Reinhard Heydrich - was almost thwarted when it jammed. This problem also occurred with the German MP40 magazine, copied by the Sten gun designers.

Canadian infantry battalions in North-West Europe held spare Sten guns for special missions and the Canadian Army reported a surplus of the weapons in 1944. The Sten was not used in Italy due to constraints on the shipping of ammunition; .45 ACP was already being used in theatre by the US Army and a requirement for 9 mm would have been in competition with limited shipping space.

The Sten saw use even after the economic crunch of World War II, replacing the Royal Navy's Lanchester submachine guns into the 1960s and was used in the Korean War including specialist versions for British commandos. It was slowly withdrawn in the 1960s and replaced by the Sterling SMG in British Army service, while Canada adopted a similar weapon, the C1 SMG to replace the Sten.

In the 1950s "L numbering" came into use in the British Army for weapons - Stens were then known as L50 (Mk II), L51 (Mk III) and L52 (Mk V).

One of the last times the Sten was used in combat during British service was with the RUC during the IRA border campaign of 1956 - 1962. In foreign service, the Sten was used in combat at least as recently as the Indo-Pakistani War of 1971.

In 1971 various marks of Stens were used by guerilla fighters during the Bangladesh Liberation War.

A number of suppressed Stens were in limited use by the US Special Forces during the Vietnam war, including circa 1971, by the US Rangers.

In 1984, Indira Gandhi was assassinated by two of her Sikh bodyguards, one of whom emptied the entire magazine of his Sten into the Prime Minister at point-blank range.

In the Chinese Civil War, both sides used the Sten.

Criticisms

The main flaw of the Sten lay in its magazine. For some reason, co-designer Harold Turpin simply copied the magazine of the German MP40 without alteration, and had adapted it for the Sten. Unfortunately, by this, the lips of the magazine became critical to the feed of the ammunition. The slightest damage was often enough to cause a stoppage, a curse that often beset the Sten when the weapon was fired on automatic. Nevertheless the Sten was a most reliable weapon when kept in good condition and could generally be relied upon to fire with very few such stoppages.

The MK II and MK III Stens could accidentally discharge if dropped whilst the gun was cocked. This was particularly true of early Stens using bronze bolts, where the sear projection underneath the bolt could wear down more easily than ones made of case-hardened steel.

See also

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