Sten MkI & MkI*: The Original Plumber’s Nightmare

The Sten gun was designed by RSAF Senior Draftsman (sorry, Draughtsman) Harold Turpin in December, 1940. He sketched out a simple trigger mechanism on December 2, showed it to Major Reginald Shepherd the next day, and then finished out the rest of the submachine gun design that week. The first prototype gun was completed on January 8, 1941 and it was tested by the Small Arms School that same month. The design was approved for production (alongside the Lanchester) March 7th, 1941 and the first of 300,000 Sten MkI guns was delivered to the British military on October 21, 1941. The MkI and MkI* Stens were all manufactured by the Singer sewing machine company in Glasgow, with three contracts for 100,000 guns each issued in 1941.

The Sten was the British response to a dire need for a large number of cheap infantry weapons, and it served that purpose well. The MkI was quickly followed by a somewhat simplified MkI*, which discarded the unnecessary flash cone and the wooden front grip. An even simpler MkII optimized for mass production followed, along with a MkIII. As the end of the war approached the MkV was introduced which had much improved handling, and it would remain in service until the 1950s, when it was finally supplanted by the Sterling.

Many thanks to the Royal Armouries for allowing me to film and disassemble these rare submachine guns! The NFC collection there – perhaps the best military small arms collection in Western Europe – is available by appointment to researchers:

You can browse the various Armouries collections online here:


  1. The necessity for the STEN is a cautionary tale warning of the dangers of failing to prepare for war.

    Not to mention, preparing for the wrong war…

    Neither the British nor the French really pulled their heads out of their tactical/operational asses for the early phases of WWII. They more-or-less ignored what happened in Poland, and the fact that the Germans were happily analyzing and correcting all the issues they’d discovered during that campaign whilst the Allies sat on their asses doing their laundry along the defense lines.

    Had either nation been on their toes, the debacle which was France, 1940 would have likely happened, but along different lines. The way that it did work out may have been for the best, because if Germany had instead become engaged in a lengthy blood-letting campaign in Western Europe, then the Germans would have had to keep the Soviet Union and Stalin happy while everything was going to hell in a handbasket again, which would have left a nice opening for Stalin to stab Hitler in the back… Which would have been a WWII with an even worse potential outcome.

    It’s odd to consider, but the defeat in France in 1940 may have actually been the “Best Case” scenario for most Europeans… And, world history. Allowing Hitler to turn on his ally by losing France might have been the Ju-Jitsu move of all time…

    Of course, you can make up all sorts of counter-factuals, but there you go: We may already live in the best of all possible WWII outcomes.

    • The almost unbelievably rapid advance of German forces in the first week of Operation Barbarossa was largely Stalin’s fault. It was “three strikes” like a baseball game.

      Strike one; Stalin’s purges of the army’s officer and NCO corps left the Russian Army as basically a leaderless mass. What “leadership” there was came mainly from the zampoliti, the “poliical officers”, backed up by the guns of the NKVD. (The SS has nothing on those bastards in the “atrocity” department.) Their command decisions were mostly basted on Marxist/Leninist political doctrine, a problem that dogged the Russian military clear up to 1991.

      Strike Two; In anticipation of his own invasion of Germany through the “soft underbelly” of the Sudetenland, Stalin had ordered most of the army’s units out of their carefully-prepared defensive line and forward to their jumping-off points. The Russian invasion was apparently originally planned for late May, but a combination of weather and Stalin’s vacillation delayed it, giving the Wehrmacht time to move first. (Hogg’s Law; Just because you’re getting ready to attack, there’s no rule prohibiting the other fellow from having a go at you first.)

      Strike Three; As part of his dilatory act, Stalin ordered the Russian Air Force to their forward fields but kept them grounded to save fuel. Most of their planes were destroyed on the ground in the first two days of the invasion as a result.

      If Stalin hadn’t first gotten “buck fever” and then an attack of “wait and see”, the German invasion would have been well inside Russian territory when it ran into a well-planned defense, with more armor and aircraft than Germany had, backed up by heavy artillery.

      Von Bruchmuller could have told them how that would likely have turned out.

      clear ether


      • Eon:

        I am not at all convinced that Stalin was planning an attack on Germany in 1941. Maybe things would have changed in 1942, but in 1941 the USSR was in no fit state to attack Germany. It took them 18 months until Stalingrad to start rolling the Germans back.

        • If you examine what Stalin was doing with it all, the thing that stands out is that he seems to have been planning on Germany and the Allies being deeply embroiled in conflict in the West, just as in 1914-18. By about ’42, which was when I believe he did mean to take advantage of that set of circumstances, he’d have been well-set to have conducted an invasion of Germany from the East, and we’ve no idea at all how that would have worked… Allies would have had their forces worn down, Germans would have been in a similar situation, and… Yeah. I doubt Stalin had plans to move in on it all during ’41, but he outsmarted himself by egging the pudding via directing the COMINTERN assets he had in France to cripple the defense efforts, particularly by the Aviation Minister. The French actually had warehouses full of decent fighters that never got into the Battle of France, among other things.

          So, 1941? No, but he did have designs on the West that you can plainly make out through his force dispositions and all the rest. In Stalin’s case, “…the bear blew first…” Which was probably due to the fall of France happening so quickly and unexpectedly. Overall, as I say… We probably do live in the best of all possible outcomes from the disastrous conduct of WWI and the Versailles peace.

          Which is a very, very ugly indictment on the leadership of those times and the eras after. I don’t know why we didn’t put the lot of them on trial for crimes against humanity, particularly the incredibly incompetent WWI French and British leadership that kept pouring men into useless battle… If you squint your eyes, and look at it right, you can see a reflection of the current BS going on in Russia vs. Ukraine. Putin truly is the heir of the Tsars, which he seems to think is best demonstrated by getting the youth of Russia killed in job lots for no good purpose.

          Which, in the end, is a reflection of our own cupidity as nations: We all ought to demand better from our leadership, and hold them accountable when they do these things. Congress, in the US? Why in the hell were we so tolerant of those assholes first getting into a war in Vietnam that the military spent much of the late 1950s and early 1960s advocating against, then getting 50,000 Americans killed, God knows how many wounded and given lifelong psychic injury, along with all the South Vietnamese victims… Which they then pissed away by refusing to adhere to the treaties that they’d negotiated to end our involvement? 50,000 dead Americans, and we kept right on electing those assholes like Kennedy… Hell, we’ve even made Joe Biden, who was one of the very architects of the disastrous abandonment of South Vietnam, President.

          You seriously couldn’t sell novels with this crap as plot elements. “Not credible; no nation could be that stupid…”

          Unfortunately, the record of history shows that not only can they be “that stupid”, the stupidity is both endemic and apparently, very easily forgotten…

          All of these political assholes should have been tried and executed for incompetence and crimes against their own people, not to mention humanity in general. I find myself looking at what happened to those Dutch politicians back in the day, and thinking “Well, they were on the right track, I suppose…”

          We need more Johann de Witts spread liberally across history, if only as Byng-like “encouragements to others”…

  2. I’d often wondered why the receiver tubes for the STEn and the sterling were so skinny, when a fatter tube would have allowed both a slightly shorter bolt saving some overall length, and more clearance between the barrel and the front hand guard / jacket

    now I know

    it was a feature inherited from the tube that was available

    a bit like the standard gauge of railway being inherited from the gauge of the mine tramways of North East England

    Those in turn being inherited from carts made to fit the ruts cut in the Roman roads by Roman chariots, that were wide enough to fit behind a Roman horse’s arse.

    • Not to be “that guy”, Kieth, but…

      That tale about Roman chariots being the reason for the laughably “standard gauge” has been refuted innumerable times since I first repeated it myself, as a high school student. I had picked up that same story as a bored kid and voracious reader, so I repeated it in class. Turns out, new history teacher was a bit of a rail enthusiast, and I was the one who got schooled…

      Decent summation, a charitable one, of the issue:

      In short, while they’re close to the same, the reasons aren’t because of Roman ruts leading directly to rail gauge, but because the physical constraints that led to both standards were much the same… 4’8″ being the size you need to have between rails because they were based on horse-drawn mine cartways, which needed to be that width because 5 feet was the minimum distance for horses to operate in, less 2 inches on each side for the rails…

      It’s more a thing of repeated re-evolution, rather than there being an actual connection, sadly. Though, it is a damn good story…

    • The STEN bolt is rather stout for a 9mm – fatter than the TEC / AP9 (which has a short little potato of a bolt) or the PPS43, and MUCH fatter than an AR9.

      Its overall length is a result of the silly rear trigger (a common plague among second-generation SMGs).

      • That rear trigger was largely inherited from first generation SMGS, the difference being that most of them had wood stocks with semi-pistol grips like typical bolt-action rifles.

        So the placement of the trigger group relative to the bolt was more like the rifles of the day, disregarding the differences between a rifle bolt (such as a Mauser 98) and the SMG bolt (such as an Mp28). It just didn’t look the same on something without a wooden rifle-type stock.

        The outlier was the Thompson. Its setup may have been copied from the Mauser c/96 pistol. It seems to have inspired the French MAS36 and MAT49 SMGs, especially the latter. As well as the little known Argentine Halcon series.

        The German Mkb42/Mp44/StG44 series also seems to have derived its control/magazine interface arrangement from the Thompson.

        So indirectly at least you can probably say that the Thompson was a forerunner of the AR-10/AR-15 family, at least in terms of ergonomics.

        clear ether


        • That could generously be granted as a reasonable excuse for the wood-stocked guns, but still absurd for pistol-gripped SMGs.

          The Thompson isn’t that much of an outlier; most bolt, lever, and pump guns (many of which have straight wood stocks) have the trigger guard close behind the mag, as do the BAR, Garand, Carbine, MAS-38, and many/most autopistols of the C96 generation.

          • In the case of the Sten, keep in mind that it was following the basic pattern of the only other SMG “Made in Britain by British Labour” at the time, the Royal Navy’s Lanchester Machine Carbine.

            And the Lanchester in its turn was more-or-less a direct copy of the German Mp28.

            The Sten qualifies as a late first generation SMG in layout while being an early second generation SMG in terms of construction methods. Call it a generation one point five.

            As for the TSMG, all the rifles etc. you mentioned have one thing in common; they did not have a full pistol grip separate from the wood stock. Except for the MAS38 SMG, which very likely “borrowed” that feature from the Thompson.



    • KiE, bear in mind that sten bolt is drilled in the back, so some empty dead space there, so it could have been theoret. made shorter to begin with

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