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 their arsenal at the same time. After the start of the war and to 1941 (and even later), the British purchased all the Thompson submachine guns they could from the United States, but these did not meet demand, and Thompsons were expensive, the M1928 costing $200 in 1939 (and still $70 in 1942), whereas a Sten would turn out to cost only $11. 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 an 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 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 the Birmingham Small Arms Company (BSA). The Sten shared design features, such as its side-mounted magazine configuration, with the Lanchester submachine gun being produced at the same time for the Royal Navy and Royal Air Force, which was a copy of the German MP28. In terms of manufacture, the Lanchester was entirely different, being made of high-quality materials with pre-war fit and finish, in stark contrast to the Sten's austere execution. The Lanchester and Sten magazines were even interchangeable (though the Lanchester's magazine was longer with a 50-round capacity, compared to the Sten's 32.) The Sten used simple stamped metal components and minor welding, which required minimal machining and manufacturing. Much of the production could be performed by small workshops, with 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 of work. Some of the cheapest versions were made from only 47 different parts (out of 47 components, only the barrel and bolt were machined). 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 higher standard. 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 to lock the bolt in the closed position to reduce the likelihood of unintentional discharges inherent in the design. Most changes to the production process were more subtle, designed to give greater ease of manufacture and increased reliability, and the potentially great differences in build quality contributed to the Sten's reputation as being an unreliable weapon. Historian John Warwicker claimed "Exaggerated reports about the unreliability [of the Sten] were usually related to the quality of manufacture. Don Handscombe and his comrades in the Thundersley Patrol of the Auxiliary Units rated them more reliable than the Thompson SMG." Sten guns of late 1942 and beyond were highly effective weapons, though complaints of accidental discharge continued throughout the war. The Sten was replaced by the Sterling submachine gun from 1953 and was gradually withdrawn from British service in the 1960s. Other Commonwealth nations followed suit, either by creating their own replacements or adopting foreign designs. ==Design==

The Sten is a blowback-operated submachine gun firing from an open bolt with a fixed firing pin on the face of the bolt. This means the bolt remains to the rear when the weapon is cocked and on pulling the trigger the bolt moves forward from spring pressure, stripping the round from the magazine, chambering it and firing the weapon all in the same movement. There is no breech locking mechanism; the rearward movement of the bolt caused by the recoil impulse is arrested only by the mainspring and the bolt's inertia. The German MP40, Soviet PPSh-41, and US M3 submachine gun, among others, use the same operating mechanisms and design philosophy of the Sten, namely their low cost and ease of manufacture. Though the MP40 was also built largely for this purpose, Otto Skorzeny went on record saying that he preferred the Sten because it required less raw material to produce and performed better under adverse combat conditions. The effect of putting lightweight automatic weaponry into the hands of soldiers greatly increased the short-range firepower of the infantry, especially when the main infantry weapon was a bolt-action rifle capable of only around 15 rounds per minute. The open-bolt firing mechanism, short barrel and use of pistol ammunition severely restricted accuracy and stopping power, with an effective range of only around , compared to for the Lee–Enfield rifle. Stoppages could occur for poor maintenance, while others were particular to the Sten. Carbon build-up on the face of the breech or debris in the bolt raceway could cause a failure to fire, while a dirty chamber could cause a failure to feed. Firing the Sten by grasping the magazine with the supporting hand, contrary to instruction, tended to wear the magazine catch, altering the angle of feed and causing a failure to feed; the correct method of holding the weapon was as with a rifle, the left hand cradling the fore piece. The Sten's magazine, like the Lanchesters, derived from the MP28, originally to use its magazines, which incorporated the faults of the MP28 magazine. The magazine has two columns of 9 mm cartridges in a staggered arrangement, merging at the top to form a column. While other contemporary staggered magazines, such as the Thompson, feed from the left and right side alternately (known as "double column, double feed"), the Sten magazine requires the cartridges gradually to merge at the top of the magazine to form a column ("double column, single feed"). Dirt or foreign matter in this taper area can cause feed malfunctions. The walls of the magazine lip have to endure the full stresses of the rounds being pushed in by the spring. This, along with rough handling, can result in deformation of the magazine lips (which requires a precise 8° feed angle to operate), resulting in misfeeding and a failure to fire. If a Sten failed to feed due to jammed cartridges in the magazine, standard practice to clear it was to remove the magazine from the gun, tap the base of the magazine against the knee, re-insert the magazine, then re-cock the weapon and fire again as normal. To facilitate easier loading 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. The slot on the side of the body where the cocking knob runs was also a target of criticism, as the long opening can allow foreign objects to enter. On the other hand, a beneficial side-effect of the Sten's minimalist design is that it will fire without any lubrication. The selector is a push button type that actuates a sear disconnector to enable firing in semi-automatic. When firing in this mode, the bolt moves rearward tripping on the sear disconnector downwards requiring the user to release the trigger to fire the weapon again. When firing in full automatic, the selector slightly pivots and moves the sear disconnector sideways enabling the trigger to hold the sear in the firing position without interference of the bolt movement. The open bolt design combined with cheap manufacture and rudimentary safety devices also means the weapon is prone to accidental discharges, which proved hazardous. A simple safety can be engaged while the bolt is in the rearwards (cocked) position. However, if a loaded Sten with the bolt in the cocked position is dropped, or the butt is knocked against the ground, the bolt can move far enough forward to pick up a round (but not far enough to be engaged by the trigger mechanism) and the spring pressure can be enough to chamber and fire the round. The Mk. IV's cocking handle is designed to prevent this by enabling the bolt to be locked in its forward position, immobilising it. Wear and manufacturing tolerances can render these safety devices ineffective. Though the Sten was somewhat prone to malfunction, in the hands of a well-trained soldier, who knew how to avoid the Sten's failings, they were less of a liability as otherwise may be suggested. According to Leroy Thompson, "Troops usually made the conscious choice to keep the Sten with a magazine in place, based on the assumption that they might need it quickly. It might, then, be argued that more troops were saved by having their Sten ready when an enemy was suddenly encountered than were injured by accident. The Sten was more dangerous to its users than most infantry weapons, but all weapons are dangerous". == Variants ==

Sten guns were produced in several basic marks, of which nearly half of the total produced consisted of the Mark II variant. Approximately 4.5 million Stens were produced during the Second World 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 Philco Radio works at Perivale, Middlesex during December 1940/January 1941 in 36 days. This weapon is held by the historical weapons collection of the British Army's Infantry and Small Arms School Corps in Warminster, Wiltshire. The Mark I has a conical flash hider and fine finish. The bolt on the Mark I rotates downwards to hold it open for safety, similar to that of a bolt-action rifle (the bolt on Mark II+ variants rotates upwards). The handguard, vertical forward grip and some of the stock are made of wood. The stock consists of a small tube, similar to the Mark II Canadian. The barrel shroud has vent holes. The magazine insert is fixed to the receiver with screws (unlike the later found on Mark II+ variants that can be rotated 90 degrees for stowage). A design choice that is only present on the Mark I is that the vertical forward grip can be rotated forward to make it easier to stow. 100,000 Mark I Stens were made before production was moved to the Mark II. Mark I Stens in German possession were designated MP 748(e), the 'e' standing for . Mark I* The Mark I* (pronounced "Mark-One-Star") variant was designed to simplify production of the Mark I; the handguard, vertical forward grip, vent holes, wooden furniture and conical flash hider were removed with this variant. The Chinese M38s were made in an automatic-only configuration, unlike the standard Mark II. The M38 was made in 9×19mm and 7.62×25mm Tokarev variants. • Overall length: • Barrel length: • Weight: Mark III After the Mark II, this was the most produced variant of the Sten, manufactured in Canada alongside the United Kingdom, with Lines Bros Ltd being the largest producer. Mark V The Mark V adds a bayonet mount, and a wooden pistol grip and stock. Suppressed models Mk II(S) and Mk VI models incorporate an integral suppressor and have a lower muzzle velocity than the others due to a ported barrel intended to reduce velocity to below the speed of sound – – without needing special ammunition. The suppressor heats up rapidly when the weapon is fired, and a canvas cover was laced around the suppressor for protection for the firer's supporting hand. ; Mk II(S): Designed in 1943, the Mk II(S) ("Special-Purpose") is an integrally suppressed version of the Mk II. Captured examples of the Sten Mk II(S) in German service were designated MP 751(e). Some guns were even changed to semi-automatic only. In addition to its use in the European theatre, the Mk II(S) saw service with clandestine units in the Southwest Pacific Area (SWPA) such as the Services Reconnaissance Department and the SOE's Force 136 on operations against the Imperial Japanese Army. The Sten Mk II(S) was used by the Operation Jaywick party during their raid into Japanese-occupied Singapore Harbour. The Sten Mk II(S) also saw service with the Special Air Service Regiment during the Vietnam War. Experimental models ; Mark II (wooden stock model): This is a standard Sten Mk.II with a wooden stock attached in place of the wireframe steel stock used with Mk.IIs. This wooden stock model was never put into service, likely due to the cost of producing it. ; Mark II (Rosciszewski model): This is a Sten Mk.II modified by Antoni Rosciszewski of Small Arms Ltd. The magazine is mechanically operated by the breech block movement. The trigger is split into two sections, with the upper part of the trigger offering full-auto fire and a lower part offering single shots. It is very complex in design and was never fielded. ; Mark II (pistol grip model): This is a Sten Mk.II with a wireframe pistol grip, intended for use with paratroopers. It is compact but predictably uncomfortable to fire. ; Model T42: This is a Sten Mk.II modified with a five-inch barrel and folding stock, as well as a conventional pistol grip and redesigned trigger guard. It was dubbed the "T42" in prototype phases, but never entered service. ; Mark IV: The Mark IV is a smaller variant of the Sten, comparable in size to a pistol, and never left the prototype stage. It uses a conical flash hider, a shortened barrel, and a much lighter stock. The weapon is also fully automatic and there is no semi-automatic function on the gun. It was made in the United Kingdom after World War II and was a prototype weapon never used as it was deemed impractical. It was designed for military policeman in post-war Germany to be fired one-handed. Only one was ever made and it is currently held at the Royal Armouries Museum in Leeds, United Kingdom. Another variant comes with a pistol grip section based on the Ballester–Molina .45 pistol. The Halcon ML-57 is a simpler derivative of the Sten gun of Argentine origin that is fed from a vertically inserted magazine. ;Indonesia: Indigenous copies were produced at the former Demakijo (alternatively Demak Ijo) sugar mill in Sleman Regency and other factories throughout Yogyakarta in 1946–1948 for the Indonesian Army during the Indonesian National Revolution. The indigenous Sten has the trigger group closer to the magazine insert. Another variant of the indigenous copies was named Pren Gun, from the portmanteau of Pranggono (the designer) and Sten gun. Pren guns were made at a factory in Tirtomoyo, Wonogiri Regency for the Surakarta-based (Student Soldiers Combat Engineers). The design is similar to the Sten Mk II with wire stock and additional flash hider. ; Israel: Copies of the Sten Mk II and Sten Mk V were clandestinely manufactured in Tel Aviv and on various kibbutzim in 1945–1948 for use with Haganah and other Jewish paramilitary groups. ; France: The French R5 Sten, manufactured in Limoges by the motorbike and aeroplane engine manufacturer (SNECMA), comes with a shorter barrel, a forward pistol grip and distinctive wooden stock, although its greatest improvement is a sliding bolt safety, added to secure the bolt in its forward position. Dimensions were converted to the metric system, so the parts are not interchangeable with the Sten. From an initial target of 10,000 to 20,000 copies, 8,100 R5s were produced between late 1944 and November 1945. They were delivered to the former FFI units of the French Liberation Army and some were used during the Western Allied invasion of Germany and the First Indochina War.Other variants were made and tested by MAC () shortly after WWII with an unusual stock shape that proved detrimental to the user's aim. Internally it is basically a Sten gun but has two triggers for semi/full auto, a grip safety and a foregrip that uses MP40 magazines. Another has a folding stock with a folding magazine insert. The trigger mechanism is complicated and unusual. Neither of these prototypes had any kind of success and MAC closed its doors not long after their conception. ; Norway: The Norwegian resistance, under the leadership of Bror With, created a large number of Sten guns from scratch, mainly to equip members of the underground army . as one of the weapons his groups of commandos and resistance fighters used effectively against German troops. ; Denmark: Several groups in the Danish resistance movement manufactured Sten guns for their own use. BOPA produced around 200 in a bicycle repair shop on (Old Køge road), south of Copenhagen. produced about 150 in workshops in Copenhagen, while employees of the construction company Monberg & Thorsen built approximately 200–300 in what is now the municipality of Gladsaxe (a suburb of Copenhagen) for use by Holger Danske and others. The resistance groups 'Frit Danmark' and 'Ringen' also built significant numbers of Stens. ; Poland: From 1942 and 1944, approximately 11,000 Sten Mk IIs were delivered to the by the SOE and Cichociemni. Because of the simplicity of the design, local production of Sten variants was started in at least 23 underground workshops in Poland, with some producing copies of the Mark II, and others developing their own designs, namely the '', the KIS'', and the more significantly altered . Polski Stens made in Warsaw under the command of Ryszard Białostocki were built from parts made in official factories, with the main body of the design being made from hydraulic cylinders produced for hospital equipment. To help disguise their origin, the Polski Stens were marked in English. It externally resembles the Sten but has twin pistol grips and folding stock resembling those of the German MP40. Australian and NZ troops however preferred the Owen gun which was more reliable and robust in jungle warfare. A Mk II version was also produced which is of different appearance and which makes more use of die-cast components. 20,000 Austens were made during the war and the Austen was replaced by the F1 submachine gun in the 1960s. The "Rotary Magazine Sten" is a vertically fed Sten which uses a modified Sten bolt, which can use either PPSh-41 drum magazines or stick magazines. The FRT gun is essentially a Suomi KP/-31 that uses a Sten trigger mechanism. All SaskSten guns fire from an open bolt. ; Soviet Union: A less known experimental variant, the Volkov-Chukhmatov uses a vertical tandem magazine. ;Taiwan: During the 1950s in the 39th year of the Republic of China, the 44th Arsenal developed a prototype Sten with a folding dadao blade known as the Type 90. This example uses a rear pistol grip and an inline tube stock with folding blade catch and extended barrel shroud. ; Vietnam The Vietnamese Arsenal copied the Sten gun during the First Indochina War, and the Viet Cong made them during the Vietnam War. Conversions The Sten Mk.II can be converted to take 7.62×25mm ammunition by changing the barrel, magazine, magazine housing and bolt. Some of them were imported to the US before 1968. While all types of 7.62×25mm ammo can be used, those made in the former Czechoslovakia are made for small arms that can handle high velocity ammo Anyone using the converted Stens are not advised to use Czechoslovak-made ammo. ==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 sometimes questionable reliability made it unpopular with some front-line troops. It gained nicknames such as "Plumber's Nightmare", "Plumber's Abortion", or "Stench Gun". The Sten's advantage was its ease of mass-production manufacture in a time of shortage during a major conflict. Made by a variety of manufacturers, often with subcontracted parts, some early Sten guns were made poorly and/or not to specification, and could malfunction in operation, sometimes in combat. The double-column, single-feed magazine copied from the German MP28 was never completely satisfactory, and hasty manufacturing processes often exacerbated the misfeed problems inherent in the design. A common statement heard from British forces at the time was that the Sten was made "by Marks and Spencer out of Woolworth." British and Commonwealth forces in the early years of the war often extensively test-fired their weapons in training to weed out bad examples; a last-minute issue of newly manufactured Stens prior to going into action was not welcomed. The MK II and III Stens were regarded by many soldiers as very temperamental, and could accidentally discharge if dropped or even laid on the ground whilst the gun was cocked. manufactured (well-made) Sten copies postwar into the early 1950s, evidently believing in the basic reliability and durability of the design. A well-maintained (and properly functioning) Sten gun was a devastating close-range weapon for sections previously armed only with bolt-action rifles. In addition to regular British and Commonwealth military service, Stens were air-dropped in quantity to resistance fighters and partisans throughout occupied Europe. Due to their slim profile and ease of disassembly/reassembly, they were good for concealment and guerrilla warfare. Wrapping the barrel in wet rags would delay undesirable overheating of the barrel. 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 the similar Błyskawica SMGs were manufactured in occupied Poland). armed with a Sten Mk II SMG, France, 1944 Canadian infantry battalions in northwest Europe retained spare Sten guns for special missions and the Canadian Army reported a surplus of the weapons in 1944. 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 from British Army service in the 1960s and replaced by the Sterling SMG; Canada also phased out the Sten, replacing it with the C1 SMG. The Sten was one of the few weapons that the State of Israel could produce domestically during the 1948 Arab–Israeli War. Even before the declaration of the State of Israel, the Yishuv had been producing Stens for the Haganah; after the declaration, Israel continued making Stens for IDF use. The opposing side also used (mostly British-made) Stens, particularly the irregular and semi-regular Arab Liberation Army. In 1954, the British Army began using "L numbers" to type-classify weapons and related stores; while Sten guns then in-service were not redesignated, L numbers were applied to later drill purpose variants of the Mk II, Mk III, and Mk V (L50A1 Drill Purpose Machine Carbine, L51A1 Drill Purpose Machine Carbine, and L52A1 Drill Purpose Machine Carbine respectively). 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. Sten guns were widely used by guerrilla fighters during the 1971 Bangladesh Liberation War. In 1975, President Sheikh Mujibur Rahman and his family members were assassinated using Sten guns. A number of suppressed Stens were in limited use by the US Special Forces during the Vietnam War, including c. 1971, by the United States Army Rangers. A 9mm Sten was used by the assassins in the 1975 assassination of Sheikh Mujibur Rahman in a military coup, which was the most common submachine gun model in service with the Bangladesh Army during the mid-1970s. In 1984, Indian prime minister Indira Gandhi was assassinated by two of her bodyguards, one of whom fired the entire magazine (30 rounds) of his Sten at point-blank range, of which 27 hit her. In the Second Sino-Japanese War and the Chinese Civil War, both nationalists and communist Chinese forces used the Sten. Some Stens were converted by the communists to 7.62×25mm ==Users==

• : Used by the Albanian National Liberation Army during World War II. The weapons were supplied by the British SOE. • : Modelo C.4.. • : Locally produced during World War II. • : Extensively used during 1971 war. • • • : Locally produced during World War II. • : Central African Republic Police had 10 Stens in 1963 • • • : Fidel Castro praised the Canadian Sten gun in his 1958 interview with Erik Durschmied • • : Most used by communist forces had their Stens converted to 7.62x25 calibre. • : Used during World War II by the Free French forces, the French Resistance and some captured from the Resistance were used by the pro-German Milice française. Still used after World War II. • • • • : Used by republican Forces. • : Used in the 1947–1949 Palestine war • : Sten guns were supplied to the Italian resistance movement by the SOE, along with the United Defense M42 submachine gun supplied by the OSS during the Italian Campaign. These guns, along with the Berretta M38A, were used by the Italian partisans until the end of World War II. • • : Used by the regular police paramilitary GSU, army paratroopers; replaced by G3A3/4, M4 and HK416. • Kingdom of Laos: • • : Still in service in 2006. • • : Used some captured Stens during World War II, under the designations MP 748 (e) for the Mark I to MP 751 (e) for the Mark V. From late 1944, they produced an almost identical copy of the Mk II, the Gerät Potsdam (Potsdam Device) and a modified version, the MP 3008, as last ditch weapons. • • • : Canadian Mk II and Chinese M38 copies. • : Used by the Norwegian resistance from 1940–1945. The guns came to the resistance groups by air (supply drops). Used by the Army after the war. • : Việt Minh and Viet Cong • • : Used by the Recognized Guerrilla Units during World War II. • : Used by Polish Armed Forces in the West and main resistance army in occupied Poland, the Armia Krajowa (Home Army). The majority of the resistance's Stens were dropped to Poland in SOE supply drops, but some of the Polish Stens were produced in the occupied country. Polish engineers also designed their own Sten version, the Błyskawica submachine gun. After the war, it was used by many anti-communist partisan groups (cursed soldiers). • : Known as m/43. • • • • : Used by SWAPOL during the South African Border War. • • : The Tibetan Army purchased 168 guns in 1950. • Also used after the war. Non-state groups • Front de libération du Québec: Stolen from Canadian armouries. • FNLA • The Provisional IRA and Official IRA • Some were supplied to the Bulgarian Communist Party during WWII • Mau Mau guerrillas used captured Stens. ==Notes==