This British design of a submachine gun that appeared in early WWII was loathed by troops but had a very significant impact on the weapons industry and is perhaps the best example so far of something that can be produced to replenish the arsenal of any fighting force, no matter how dire the conditions for its survival in the battlefield are.
More than a weapon or a weapons family we have to consider the Sten as a system that went web beyond the borders of the country of their creator.
The design of the Sten submachine gun began at a time in which the WWII scenario was not favourable for the allies and thus it can and should be considered as an emergency or interim design that later became standard. A true, successful survival weapon whose many defects became virtues in many cases. Then, the British forces only had a handful of Thompson and Lanchester submachine guns, both designed by means of inter-war criteria. These were effective but heavy and expensive weapons, not well suited for confronting the mobile armies that the Germans used in their blitzkireg. So the Sten was born. It was a machine designed to be produced with non-critical raw materials in almost any sort of machine shop. In essence, it was what we know as the produce of a "jungle factory" and was constructed and shipped by the millions to troops and guerrilla movements. Moreover: It remained in active duty for decades, and it is known that it was kept in the Royal Navy's arsenals up to the mid sixties, and in 1971 was used during the war between Pakistan and India. Some pictures suggest that the Zapatists rebels in Mexico used units of the Mark IV B version or some clone of it as late as 1995,and while it sees strange that they used precisely the less-abundant version of the Sten - the Mark IV was built in small numbers for special operations - cloning shouldn't surprise anyone because this "abortion gun" as some called it could be reproduced almost anywhere right down to the smallest details.
A 3D view of a Sten Mark II, the most numerous version of this weapon.
The Sten is now considered obsolete but it was seen almost in the same light during WWII and still, it survived other much better designs, technically speaking, like the PPSh M1941, MP40 or the proverbial Thompson, or Tommy Gun because this shortcomings, as we said, ended up for the most part as virtues, like:
The weapon was unsafe: The way in which it was designed made it possible for some specimens to shoot spontaneously when dropped to the floor or shaken violently. There are many reports of accidental deaths. However, this simplicity made it extremely easy to manufacture at a cost of eleven dollars of that time, per unit.
It imported defects from the German MP40 from which it copied the ammunition magazines: The Erma / Schmeisser submachine gun tended to jam because the long magazine was used by soldiers as a hand grip, and often hit the ground or obstacles. Slowly, magazines as well as components in the weapon itself began to bend and suffer wear and tear, and that led to jamming. The same problems appeared on the various Sten guns for the same reason, although the fact that it was compatible with German ammunition as well as magazines made it especially good for guerrilla fighters, special operatives and troops on fast advance, making it also possible to benefit directly from the German war effort.
Finishing was not good at all: Stens were horrible, but aesthetic considerations in a war machine are secondary. The lack of complicated or expensive processes added to the simplicity of production. Different, locally produced versions of these submachine guns employed native components for part such as the butts, handguards, triggers and pistol grips, so it is possible to find examples of Stens that functionally and internally correspond to one version but look like completely different things. This is particularly noticeable in the units built for the Polish, Danish and Norwegian resistance fighters in local, clandestine indeed shops. In Poland alone, about two dozen secret. "jungle factories" existed, and each one shipped scores of weapons in which non-essential items like the pistol grips were made of just about anything available.
Low quality of critical components: These weapons suffered numerous problems. And while at least in the UK some forms of quality control were in place - like using all new guns in military exercises and shooting ranges before delivering them to the front lines - practical considerations often made it imperative to distribute Stens as quickly as possible. This didn't help the weapon's reputation among trained combat troops: Soldiers feared to receive any new batch of brand new units of this weapon, but once again, this helped reduce its costs and anyway, they were so widely available that spares could be procured in almost any circumstance.
The ammunition: The British designers and logistial authorities selected for this weapon the 9mm Parablelum cartridge employed by German and Italian forces. Until then, the British used the .45 ACP for their submachine guns. Pistols and revolvers. The reasons for choosing the 9x19mm cartridge that now is a NATO standard go beyond its ballistic properties and should be found in logistics: It was then easier for the British to use the huge quantities of bullets captured to their enemies and start producing more locally. A 9mm cartridge case is also cheaper than a .45 ACP because it is smaller and requires less raw material. Interestingly, Parabellum cartridges have been produced with copper, steel and aluminium, and the adoption of this ammo for the Sten contributed more than anything else to the diffusion of the Parabellum around the world despite that it was invented in 1902 for the Luger pistol.
The versions produced by the British are:
Prototype: The first Stens were handcrafted and used for obvious testing and to develop the industrial methods that would be employed in the construction of the weapon.
Mark I: A strange looking weapon with a large, conical fire suppressor that sports an oblique cut designed evidently to act as a muzzle compensator in order to control better the gun while firing in fully automatic mode.
Mark I*: The design was simplified somewhat to allow for cheaper production. Several components of the weapon were take out.
Mark II: With this version the weapons system reached its maturity. This one is a far simple machine than the prior version. Several components were eliminated while its designers strived to simplify production. This is also the version that was constructed in the greatest number and the one most copied and cloned.
Mark II S: This version was produced with a shortened barrel, an integral silencer and a bronze bolt. It was never intended to be fired automatically; it's components were not designed to survive such a firing mode for long.
Mark III: This is the cheapest and most simplified version of all. It wasn't the most numerous because when it was first delivered, tactical requirements were not as desperate as before. It was also the last version that used the 540 rounds-per-minute cadence that gave the Sten its peculiar sound. Later versions shot 575 RPM.
Mark IV: A rare variant indeed, it was produced in very small numbers. It is a compact weapon intended for special operations and due to their nature it is likely that the real usage of this model will not see the light for a while, if it ever was used in combat. Two sub-variants were produced, identified as A and B. Both used a short, conical flash suppressor, were shorter than regular Stens - variant B was almost a bull-pup design - and quality was somewhat better. The B variant inaugurated a tendency seen in posterior British weapons such as the EM2 .280 and the SA80, related to shortening the weapons using the bull-pup format. In the case of the B variant, this was firstly accomplished by changing the position of the trigger and pistol grip as related to the rest of the operating mechanism of the gun.
Mark V: As the war started winding down, this version was created in order to provide soldiers - especially paratroopers - with something better to handle. Early units of this variant, however, were manufactured under poor quality standards and the weapons didn't last long. However, these Stens served in the Korean war and slow withdrawal from British service began in 1953, as the L2 Sterling was issued as the new standard submachine gun.
Mark VI: It was essentially a Sten Mark V with short barrel and silencer. It had similar limitations than the IIS.
Except for the last two versions that were developed in the closing months of the war and the initial post-war period, each successive new model of the Sten was in fact a study of savings in materials, tooling and construction methods while at the same time, some of the most evident shortcomings were allegedly corrected. Thus, the Mark I is more complex than the mature Mark II and better in its finished look. But in a parallel fashion, as the Mark V and Mark VI were behind developed, the Sterling submachine gun made its appearance, and while somewhat similar in looks to the Sten, it was a completely new design, safer and more reliable. The Sterling slowly found its way into the UK's arsenals as well as in other countries, as more obsolete designs - including the Sten - were slowly taken out of service.
Only with the introduction oft the SA80 assault rifle, capable of fulfilling the missions of both the SLR and the Sterling SMG the reign of submachine guns in the British forces, initiated by the Sten Mark I, came to an end.
The Canadian Sten
A significant part of the British weapons industry was moved to Canada during WWII where, in addition to local companies and subsidiaries of those located in the UK, began producing material for the British and Canadian forces away from the dangerous distractions cause by German attacks. The Canadian products, for this reason were generally of visible better quality.
Mark II C: This is the version produced in Canada, of slightly better quality and with some minor changes, mostly in the butt and grip.
The Polish Sten
The Polish obtain a number of original British Stens and then went on to produce their own in two basic forms:
The Polish Sten: This was a submachine gun made in a very similar way to the original Sten, using at least in part original components and camouflaging it as British in origin. The markings were falsified to fool German intelligence. Several tens of thousands were produced in such a fashion.
Blyskawica: First of all, you should pronounce the name "buiskavitsa", since everyone that doesn't speak Polish never gets it right, Then we have to say that this weapon was designed and built entirely in occupied Poland for the resistance forces. Its design is base directly on the experience that Polish guerrilla fighters gained using Stens and German MP40s and incorporates concepts coming from those two weapons. The interesting thing about this submachine gun is that almost no tooling was required to built it, like stamping and welding, very common industrial processes that were either unavailable, expensive or too indiscrete at the time.
It is interesting to comment that Polish SMGs used many times locally-produced 30-round magazines. Normally, a German MP40 or a British Sten used 40-round magazines that were exactly the same, having the designers at the Enfield factory copied the German design to take advantage of their logistics. However, these magazines were very hard to fill up to the last cartridge so, British Stens were issued with a magazine loader, a small tool that working as a lever, helped load all the rounds inside. Naturally, such devices were not always issued in the case of derivatives built elsewhere, so a 30- round magazine seems to have become the rule in Poland.
The German Sten
The Germans copied the concept and design of the Sten and apparently were determined to improve it in some ways. Ironically, the nazi regime found itself in a situation similar to that of the British during the first years of the war. The final result is well known, but at the time, the German weapons manufacturers attempted to provide some relief buy means of various versions of their Sten clones:
Gerät Potsdam: This was the first version, identical to the Sten Mark II and most likely, being produced in a small to medium batch, a study in cheap, mass production in itself that later led to the other two versions.
Gerät Neumünster: This one was produced in small numbers and is as virtual falsification of the Sten design. Even the serial numbers were taken from allied weapons and no clear reason for this seems to be apparent. Perhaps it was destined to special units and saboteurs operating beyond allied lines, but using some captured, real Stens would have don the trick as well. So, whatever the reason, this version seems to have been a waste of resources for the Germans.
MP3008: This weapon was destined for the "People's Army" or Volkssturm, a ragtag military formed by all those who could not form part of the regular army due to age or whatever. Naturally, the Volkssturm was a second-rate fighting force equipped with equally low quality weaponry and equipment. In many cases they didn't even have uniforms. For this organisation, German authorities provided two basic submachine gun designs, apart from the classic MP40 and captured models such as PPSh M1941, Italian Berettas, original Stens and so on. In one hand, they used 9mm Parabellum ammunition and the corresponding weapons, and o the other hand, guns based on the 7,92 Kurz cartridge and magazines coming from the new Stg44 assault rifle. Volkssturm units were not equipped with these modern, then hew type rifles, but the magazines and bullets did reach the militia and were applied in the VG1-5, an automatic carbine used as a submachine gun as well. This one was never accepted as a standard issue weapon by the Waffenamt, but it was used anyway. The MP3008 was delivered as part of the 9 Para batch of weapons and was very similar to the British Sten except for a few improvements or changes, such as a wooden buttstock similar or equal to that of the VG1-5, and a magazine feeder that was fixed and not movable ninety degrees, like in the case of all original Stens.
It is likely that given more time, the Germans would have evolved the submachine gun into something more akin to our modern standards, using not proper pistol ammunition but their 7,92 mm IKP (Infanterie Kurz Patrone) cartridge which was delivering excellent results. This can be deduced by the fact that the last weapon prototypes of the war, like the Stg45 prototype, while incorporating novel action systems like the rolling block mechanism, were also simplified in production methods, somewhat shortened and in general, attempted to achieve smaller weapons that could compete with submachine guns plus delivering much more. Today, some of these ideas have been applied, for several submachine guns are actually assault rifles chambered for small calibres such as 5,56 NATO and the Russian 5,45 equipped with short barrels and somewhat smaller butts.
The Sten was clandestinely produced during WWII in Norway and Denmark; these were smaller batches than those manufactured in Poland but nevertheless, the weapon was used by local resistance fighters. It was copied also in Belgium, Argentina, China, Indonesia, Afghanistan and the United States.
Something that is usually overseen is that a Sten could be manufactured in these days too at - probably - even a lesser cost that during WWII. This turns the "Stench Gun" as it was sometimes called into a usable design for any sort of terrorists or armed groups elsewhere and perhaps, only the worldwide availability of Kalashnikov models stopped that short from happening, but it should not be surprising if these peculiar submachine guns appear again and again in many battlefields.
The Sten was never a brilliant weapon, but the reason why it is still remembered is because it simply had brilliant shortcomings.
This Youtube video shows how a Sten is prepared to FIRE in semi and full auto modes. It is also easy to see how the magazine feeding door can be moved ninety degrees down or to the side of the machine gun.