A Police SMG Upgrade: the MP-18 System Schmeisser

When the MP-18 was issued by the German Army in World War One, it used the then-in-production Luger “snail drum” magazines. These were expensive, awkward, and generally not ideal. Once the war ended, Hugo Schmeisser quickly developed an alternative box magazine design. The initial goal was simply to update existing guns to use the new magazines by simply replacing their magazine housings. This was done, but not as quickly or universally as many people would expect. The Army never did update its MP-18s (snail drum models were still used in some places in World War Two). Some of the various German police forces did make the change, but often not for a decade or more after the end of the war.


  1. If box magazines and housings had been developed from the get-go, the conversion wouldn’t be needed. As it were, logistics of 1918 dictated that nobody reinvented the wheel, and thus the issue at hand. Converting all examples of the MP-18 and accounting for the proceedings would be a nightmare (which batches of guns went to which neighborhoods?!). I could be wrong.

  2. The internal conditions of Germany in 1919 can be gauged by the fact that the Army couldn’t have submachine guns, but the police could

  3. A couple more comments

    1) Strictly speaking, the 9mm Parabellum is a 7.65mm case with the bottleneck removed to create a straight sided round, not “7.65mm being a necked down 9mm”

    2) My impression is that the first major use of the submachine gun after the Great War was in the Gran Chaco (“Green Hell”) War in the early Thirties between Bolivia and Paraguay, foreshadowing WW2.(The Bolivians had employed German Soldiers of Fortune – most Great War veterans – to train their troops, which explains the prevalence of German arms. BTW, one of the Germans was the notorious Ernst Rohm)


    Although the Bolivian standard was the MP28,

    “Bolivian infantry forces were armed with the latest in foreign weapons, including DWM Maxim M1904 and M1911 machine guns, Czech ZB vz. 26 and Vickers-Berthier light machine guns, Mauser-type Czech VZ-24 7.65 mm rifles (mosquetones) and Schmeisser MP-28 II 9 mm submachine guns. At the outset, the Paraguayan troops used a motley collection of small arms, including the German Maxim, the British Vickers, and the Browning MG38 water-cooled machine guns, and the Danish Madsen light machine gun. “The primary service rifle was the M1927 7.65 mm Paraguayan Long Rifle, a Mauser design based on the M1909 Argentine Long Rifle and manufactured by the Oviedo arsenal in Spain. The M1927 rifle, which tended to overheat in rapid fire, proved highly unpopular with the Paraguyan soldiers. Some M1927 rifles experienced catastrophic receiver failures, a fault that was later traced to faulty ammunition. After the commencement of hostilities, Paraguay captured sufficient numbers of Bolivian VZ-24 rifles and MP 28 submachine guns (nicknamed piripipi) to equip all of its front-line infantry forces.”

    my understanding is that late in the war, the Bolivians were buying about anything they could get so you may find some MP18’s with South American pedigrees

    “Submachine Guns of the Gran Chaco War

    While small numbers of submachine guns had been in service with various armies since 1917, in general their tactical role was not understood. But the Chaco War would show that submachine guns were the perfect weapon for the close-range combat in heavy terrain and for defending fortified positions against attack that characterized much of the conflict.

    Using the income from the nation’s lucrative mining industry, beginning in the 1920s the Bolivian army had purchased an assortment of submachine guns from American, Austrian, Finnish and German sources. Among the more common were the Bergmann MP 18.1, MP 28 and MP 35; Soumi m/26 and m/31; Steyr-Solothum SI-100; Erma EMP; CZ ZK-383; and Thompson M1921.

    While the Paraguayan army possessed a few MP 28s and EMPs at the outbreak of the war, as with other small arms, they were soon fielding large numbers of captured Bolivian submachine guns. These lightweight, fast-firing weapons proved perfect for the Paraguayans’ fast moving, guerilla style of fighting and were highly prized whenever they–and sufficient ammunition–were captured.

    While the most common caliber was 9mm Parabellum, some of the Bergmann MP 28s and the Suomi mill were chambered in 7.65mm Parabellum. Additional MP 28s in 7.63mm Mauser were used while some Steyr-Solothum SI-100, and the M1921 Thompson, where chambered for the .45 ACP.

    Many of the European military observers attached to the Bolivian and Paraguayan armies noted the use of the submachine gun in the conflict but–except for the Germans, it would seem–most thought its effectiveness was due to the unique circumstances of the fighting in the Chaco and would have no effect on established European military doctrines. It wasn’t the first time they were wrong…. and it wouldn’t be the last!”

    • I don’t know how much even the Germans applied the lessons of the Chaco war to their own doctrine. The MP 38 and MP 40 were never very common weapons in German inventory not counting paratroops and military police. Infantry squads had only one submachine gun, which really wasn’t that many compared to for example the late WW2 Soviets. It is noticeable that the Germans only made about one million MP 38 and MP 40 combined, whereas they made about 10 million Kar98k rifles.

      For example the Finnish Army determined in 1944 that in infantry squad should have at least three submachine guns. There of course was not enough Suomi SMGs to fulfill that apart from Jaeger “elite” units, but it was the ideal. By late 1950s before the official adoption of the assault rifle (Rk 62) that had risen to no less than five. Most of them would have been Sten Mk II and Mk III, though, which Finland acquired from Interarmco in exchange for Carcano rifles in 7.35mm. One might find it somewhat funny that the most common SMG ever employed by the Finnish Army was not the Suomi but the Sten…

    • “The Bolivians had employed German Soldiers of Fortune – most Great War veterans – to train their troops, which explains the prevalence of German arms.”

      Yes, but even so they lost. As far as the ZK-383 is concerned, it was never used in the Chaco War because production only started in 1938.

    • “(…)1) Strictly speaking, the 9mm Parabellum is a 7.65mm case with the bottleneck removed to create a straight sided round, not “7.65mm being a necked down 9mm”(…)”
      Taking in account direction of timeline, 9×19 mm Parabellum is 7,65×21 mm necked-up.

      “(…)Many of the European military observers attached to the Bolivian and Paraguayan armies noted the use of the submachine gun in the conflict but–except for the Germans, it would seem–most thought its effectiveness was due to the unique circumstances of the fighting in the Chaco and would have no effect on established European military doctrines.(…)”
      According to https://modernfirearms.net/en/submachine-guns-history-development-technical/
      The inter-war decades produced a significant number of submachine guns, but the tactical niche for these weapons was still unclear to many military experts. It was the Chaco War, the Spanish Civil War and the Russo-Finnish Winter War of 1940 that proved the viability of submachine guns as general-issue weapons for fighting troops.

      However, regardless of the large number of available models by the start of World War 2, in most armies, submachine guns were relegated to a secondary role. For example, the very technically advanced Heer (Hitler’s Army) issued MP-38 and MP-40 submachine guns to infantry troops in proportions of about one SMG per ten bolt action rifles.

      • LUNDE Herik O. Finland’s War of Choice : The Troubled German-Finnish Coalition in World War II. Casemate, Philandelphia, 2011. Hard cover, dustjacket, 409p., photographs, maps, index.
        This tells us that the tactical philosophy of the Finnish infantry was to use the Suomi M31 as the rifle section fire support weapon. There are photos extant of the 1939-40 period showing Suomi M31 with a heavy wire(?) bipod fitted on the very front of the barrel. Later that the Finns in the front line, used every Soviet LMG that they could, with the M31 used as intended originally. All to do with money.

        • During the Winter War Finnish Army had a serious shortage of LMGs, so Suomi SMGs were given to squads with no LMG. Whether the Suomi was actually used like a support weapon is another question, and from my reading it appears that mostly it was used as a personal weapon, often by the squad sargeant. Its effective range was simply not sufficient to replace an LMG as a support weapon.

          Like you wrote it was all a question of resources. During the Continuation War large numbers of DP-27 LMGs were captured and there were more Lahti-Saloranta LMGs available, so every infantry squad could now be issued a LMG.

          • The documentary evidence extant for the Winter War, makes no doubt that it was a section fire support weapon. At the same period the Danish Army used the licence built by Madsen M31 in a identical role. Having chatted with a long time friend from UN service in Lebanon (retired as Colonel commanding the Coast Artillery, and whose father was the post-war commander of Infantry – had commanded, company, battalion, brigade, division between 1939-1944) he stating that in 1939, the Italian Army use of The Pistola Mitragliatrice Villar Perosa M1915, official named FIAT Mod. 1915, in the Apennines by the Alpine Regiments as a section weapon was followed. It was of a badly flawed concept, much as the ‘new’ USMC tactical infantry structure. He further stating that large numbers of Soviet SMG taken into service, the PPS-42 / PPS-43 considered the best. It was considered to be worthy of reverse engineering into 9mm Parabellum and taken to manufacture, but, the Armistice put the kibosh on that. Attempts to do so post war, were totally rejected out of hand. Photographic evidence, from 1942 onwards show captured from the Soviets, Thompson M1928 and of all things M50 Reising, reputed to have been both taken from knocked out tank crews.

          • “(…)PPS-43 considered the best. It was considered to be worthy of reverse engineering into 9mm Parabellum and taken to manufacture, but, the Armistice put the kibosh on that.(…)”
            Now I confused, as https://modernfirearms.net/en/submachine-guns/finland-submachine-guns/tikkakoski-m44-eng/ states that
            Significant numbers of Tikkakoski KP M/44 submachine guns were manufactured at Tikkakoski factory during 1944 and 1945, and these guns served with Finnish army for several decades after the war.

  4. Just a thought following on from @Col Beausabre’s history

    The Memoirs of Ludwig von Mises’ widow, Margit, give account of shows of force by the Austrian social Democrats and their party armed thugs in the 1920s

    Apparently the Austrian Social Democratic party had more and better weaponry than the post Saint Germaine, Austrian army.

    It’s important to note that the title of “Social democrat” meant something particularly threatening in those times.

    Unlike bolsheviks, the social Democrats were hoping to win a democratic election, however, after that election win, they planned to immediately begin the purges, expropriations and murders, in the same manner as the bolsheviks had, to build the hoped for workers paradise on earth.

    I’m not well enough read on interwar Germany, so, please correct me if this is wrong…

    I suspect that there was a similar situation, with well armed wings of the violent political parties, along with roaming groups of armed bandits and thugs.

    Out of that struggle, Röhm’s and that little corpral’s national socialist thugs emerged on top.

    I wonder whether there was any illicit trade in upgraded magazine housings to such groups?

    Possibly involving tame police stations?

    • Keith, your paragraph starting with “Unlike bolsheviks, …” is as close to reality as was Rudolf Hess’ flight to England to reach a peace agreement.

      • Second sentence is perfect description of modern post-truth media ideology – content fabricated/tailored for the “enjoyment”, or some other emotional response, one that is seldom based on facts.
        On youtube, content farm channels producing completely fake, to the point of insanity, “diy home hacks” videos amass millions of views.

      • The third series is far superior. Historically spot on, making the actual plot more relevant. Another example of high grade TV drama, from Germany, and their use of computer graphics quite brilliant.

  5. The marking “S.K. 21” on the magazine as far as I know indicates “Schutzpolizei Köslin” (a town in West-Pomerania, now Koszalin in Poland), weapon 21. The 3 below would be magazine 3 for that weapon.
    The marking of the weapon was on the top rear of the MP 18,I magazine well and, like the 1920 date, is gone with the original magazine holder.

  6. “(…)Luger “snail drum” magazines. These were expensive, awkward, and generally not ideal.(…)”
    It should be pointed that said magazines work different than say Thompson “C” drum or PPSh drum magazine. It is more akin to “rolled” stick magazine. See right half of image available here: https://twitter.com/flakfire/status/993517407967830016
    This meant a serious force was required to fully load said magazine.

  7. Single stack magazine? Looks too short. The Luger drum would have been single stack, but I suspect this is a double stack single feed.

  8. Reportedly, the original MP18 design used a box magazine of unknown design (though it’s not hard to conjecture that it would have been the familiar double-stack single column type seen here). Apparently, that was changed for the wartime production guns to use the snail “drum” in order to get it in service quicker.

  9. Ha ha ha, your name is Schmeisser and you have a patent for a high capacity double stack magazine. That’s German right? Look we’ve told you lot a million times already, go work on something safe.

  10. Well, that explains a lot.
    Namely, it’s finally clear why MP38 and followers had buggy magazines.
    Great plot!

  11. I think that the “special conditions in a specific area” in the Chaco war was just an excuse.
    All WW1 participants, and the Germans were the first to notice the effectiveness of a compact rapid-fire weapon chambered for a pistol cartridge in close combat.
    Obviously, these shortsighted figures, using horse blinders about “the war that ended all wars” (LOL), simply did not want the costs associated with the adoption and production of a new class of weapons. Especially considering the necessary changes in the structure and supply of units and the significant amount of weapons already produced during the war.
    It is remarkable (though not surprising) that today’s leaders are doing the same.
    History teaches nothing…

  12. Stiven, There’s the probably apocryphal story of one British general’s reaction to the armistice in 1918, “Thank god that’s over, now we can get back to real soldiering” that would explain a lot. As was said about the Bourbon Restoration, “They had forgotten nothing and learned nothing”

    • “Thank god that’s over, now we can get back to real soldiering”(C)

      No wonder.
      When the term “service” becomes “work”.
      And the war is just an annoying misunderstanding that interferes with wearing a ceremonial uniform and spoils the lacquer coating on the equipment. LOL

    • Still going on today, in the US Army.

      Conditions obtaining during the “War on Terror” dictated that we had to form Personal Security Detachments out of every unit that had to enable battlefield circulation for its commanders. You can’t lead what you can’t get to, and without a PSD, you’re not getting to anything.

      The problem was that forming those elements out of hide seriously detracted from the ability of the sub-units to do their missions–You were basically looking at a minimum of a squad or platoon out of every line company being eaten up for PSD duties or some other extraneous overhead BS.

      Yet… Did we learn anything from all that? Nope; just like they gave away or scrapped all the MRAP vehicles, they failed to learn the lessons and didn’t make the PSD a permanent part of the organizations. As soon as they got back to the US, it was all “Oh, we’ll never fight like that again… We don’t need to worry about rear area security, we don’t need PSDs, and we certainly won’t need to worry about IED campaigns, ever again…”.

      Thing is, see? That sort of war is how you conduct things, when you’re the weak guy taking on the stronger one. Which means we’ll never see a conflict ever again, where we aren’t dealing with being nibbled to death by ducks in the rear areas. Which are likely to include the continental US, in the future–Which nobody wants to think about or deal with. My guess is that the first serious attack on US interests will almost certainly include attacks on the off-base housing for the drone operators down at Nellis in Las Vegas, a thing that nobody is really thinking about or doing anything at all about. I mean, for the love of God… Las Vegas? How the hell are you going to winnow out the terrorists from the tourists, down there? Wouldn’t it be a hell of a lot smarter to base the drone operations out of somewhere that’s a bit more obscure, and less trafficked by foreigners? Like, maybe… Mountain Home AFB, up in Bumtuck, Idaho?

      The people running the US military are fundamentally unserious people, and delusional to boot. They simply cannot project or imagine what the enemy might do–Which is why we’ve been blindsided by IED campaigns again and again.

      • A hundred well trained/equipped commandos and five or ten million dollars would shut the U. S. down and have us at each others’ throats in a month.

    • Sorry, but, the statement is totally false, even though many would have had similar thoughts. And of course the pre-war British Army had served in peace and war in such as Ceylon, Bermuda and Jamaica, China, Singapore and the climatic “climatic hell hole” of India. The writings in professional journals between the wars was spot on, with the Germans and Americans copying much of it (as as those Swinson, Liddle-Hart, Hobart and of course Churchill), proving that they had learned a lot. And even in those financially strapped times, they improvised to a immense degree. Such as making pseudo mortars to imitate the use of Stokes 3-inch Mortar drills, by using a stove pipe with the bottom sliced in order to slide a drill mortar bomb down, and recover it. As an aside the British military did not receive a pay rise between 1922 and 1937, and during the Depression actually had a 15% pay cut.

      • “As an aside the British military did not receive a pay rise between 1922 and 1937, and during the Depression actually had a 15% pay cut…”(C)

        Let me continue this phrase.
        And as a result, they were, if not disappointed, then embarrassed.
        And the most literate of them went to look for themselves in another field. 😉
        The result was Dunkirk.
        Stalin purged his army of the most intelligent and innovative cadres through repression, and Chamberlain did it more humanely. LOL

        • A real soldier is not a car that will not go without fuel.
          A competent and motivated soldier, in an extreme worst situation, will be able to get himself water and food and ammunition. Of course, if they exist in that area at all.
          As a last resort, he will fight with captured weapons and eat the corpses of enemies. But what he will not tolerate is when they wipe his feet on him.
          These two-faced scum knew this very well, so they easily got rid of such cadres who, by natural selection, took the place of the retired officers from the aristocracy.

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