The MP 18 Submachine Gun

We have studied the evolution of different submachine guns in the last few posts, in reverse order of appearance. Today, we will study the submachine gun that started off this whole class of weapons, the MP 18 submachine gun, otherwise called the MP 18/I or the MP 18.1 or the Bergmann MP 18.1.

During World War I, tactics that were used successfully in previous wars, such as marching lines of infantry and charging cavalry, were rendered useless by artillery and heavy machine guns. With such huge firepower available, masses of infantry soldiers attempting to charge across a battlefield were practically committing suicide. This forced a change in the infantry tactics and soldiers now dug deep trenches across the battlefield and fought from inside them. New tactics were needed to fight in the trenches. For instance, battles inside trenches were fought at very short ranges because trenches were narrow and twisted. Also, since trenches often contained more enemy soldiers defending it than the attackers, it was necessary to clear the trench before the defenders could mount a counter-attack. What was needed was a small caliber weapon with a high rate of fire, but small enough to be used in narrow trenches and light enough to be carried by a single infantry man.

Heavy machine guns had a high rate of fire, but were heavy, required multiple people to move them and needed a good amount of room to operate. Besides, the range of a heavy machine gun did not matter much inside a trench. Pistols and revolvers were small and light, but didn't have a high enough rate of fire or enough ammunition capacity. Rifles were also light compared to heavy machine guns, but were longer (and heavier) than pistols and revolvers and harder to use inside narrow trenches. They also didn't have a high rate of fire or high capacity and used larger cartridges which were unnecessary in narrow trenches.

In 1915, the German authorities attempted to modify existing semi-automatic pistols, the Luger and the Mauser C96, to use larger magazines and fire in automatic mode. However, these efforts were not successful because the pistols were so light that it was hard to aim them when firing in automatic mode. The German Rifle Commission determined that a new class of weapon was required, one that could fire pistol ammunition, but was designed to fire in fully automatic mode from the very beginning.

The design team led by Theodor Bergmann of Bergmann Waffenfabrik started working on a new design to fulfill this requirement. One of the members of the small design team was a talented designer named Hugo Schmeisser. The design they came up with was adopted in the German military in 1918 and was named the Maschinenpistole 18/I or MP 18.1. No one really seems to know what the "I" designation is, but its successor was named the MP 28/II.

The MP 18/I submachine gun. Click on the image to enlarge.

Image licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license by Edmond Huet.

The MP 18 was made using high quality components and designed to use 9x19 mm. Parabellum cartridges, the same as that used by the Luger pistol. The receiver was machined from a thick tube, unlike later submachine gun models which used much thinner tubes. The bolt was also machined from a single block of steel. It was designed as an open bolt blowback weapon, a feature that was copied by practically every submachine gun designed after it, until about 1970 or so. Schmeisser had already designed several blowback pistols for Bergmann Waffenfabrik, so he adopted the same principle for a larger weapon system. Since adding a high capacity magazine to a pistol made it cumbersome and hard to control in automatic firing modes, he designed the new weapon with a traditional-style wooden body, much like a rifle, so that it would be easier to handle. A barrel shroud was added around the barrel, to counter the overheating of the barrel when fired in full automatic mode. The magazine feed was offset to the left of the receiver and the charging handle was located on the right. The weapon was only designed to fire in automatic mode, but since it had a rate of fire of around 500 rounds per minute, it was possible to fire single shots by pulling and releasing the trigger rapidly.

Interestingly, the early design for the MP 18 used a 20-round box magazine, but the German military insisted that the new weapon use a 32-round "snail" drum magazine (the TM 08 magazine), which was originally designed for the Luger pistol.

A TM 08 snail drum magazine. Click on the image to enlarge.

Image licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license by Edmond Huet.

The snail drum magazine is not a true drum magazine, but is essentially a box magazine folded into a spiral shape. The cartridges are arranged inside it in a spiral pattern and a special loading tool is required to load it. The magazines used with the MP 18 needed to have a special sleeve to prevent the magazine from being inserted too far into the weapon. This snail drum magazine was heavy, awkward and hard to load and was one of the weaknesses of the MP 18.

Nevertheless, the MP 18 was adopted by the German army in early 1918 and about 5,000 (or 10,000) were manufactured. Even though they were not used for very long, these weapons proved to be very useful in trench warfare. In fact, when World War I ended, the treaty of Versailles explicitly forbade Germany from manufacturing any submachine guns. The 32-round snail drum magazine was also prohibited from being manufactured by the same treaty. However, Bergmann Waffenfabrik continued to manufacture this weapon in secret until about 1920 and a total of about 35,000 weapons were made. After that, Bergmann sold the design and manufacturing license to SIG of Switzerland, who started to sell it as the SIG Bergmann 1920. The Swiss produced different versions that could fire 9x19 mm. cartridges (the same as the Luger) and the 7.63x25 mm. cartridges (the same as the Mauser C96). It continued to be used by police forces in the Weimar republic, as well as China, France, Finland etc. Hugo Schmeisser modified the design to use the 20 round box magazine that he'd originally designed for it, and later, 40 and 50 round box magazines were also made for it. In 1928, he modified the design to have a selector switch and this new model was called the MP 28/II.

The MP 18 was the world's first submachine gun (technically, the Italian Villar-Perosa from 1915 was also an automatic weapon firing pistol caliber ammunition, but it was originally designed to be used as a mounted weapon in aircraft). It was influential in the designs of submachine guns that followed it. For instance, it was the MP 18 that inspired the Finns to invent their own Suomi KP/-31 submachine gun that we saw in our previous post. The British designed their Lanchester submachine gun based on the MP 28 and even made it use the same magazines as the MP 18 and MP 28. The later Sten gun could also use the MP 18 box magazines. Practically every submachine gun designed after it until about 1970, used a blowback system of operation and fired from an open bolt.

While the MP 18 was an influential design, it was also heavy and somewhat expensive to produce because key parts were machined from solid steel blocks. Later submachine guns were designed to be manufactured much more quickly and at lower costs, by using stamping and spot welding techniques.

Incidentally, it is ironic that Hugo Schmeisser's name is not associated much with the MP 18, a weapon where he made very significant contributions to the design. However, his name is popularly associated with the MP 40, a weapon that he made very little contribution to. It turned out that the German War Office mandated that the MP 40 use a magazine design that he'd actually patented for the MP 18 and MP 28 and therefore, his name somehow got associated with the MP 40 and it is referred to as the "Schmeisser submachine gun" in many countries.

The Suomi KP/-31 Submachine Gun

In our last post, we had studied about the Soviet PPSh-41 submachine gun. In today's post, we will study one of the main inspirations for the PPSh-41, the Finnish-made Suomi KP/-31.

During World War I, the German designer, Hugo Schmeisser had developed the MP-18 submachine gun, which his employer, the German manufacturer, Theodor Bergmann, started to produce in his factory by 1918 and about 10,000 were made before the war ended soon after. This weapon was the first practical submachine gun used in combat (though not the world's first submachine gun). Even though this weapon was only used for a short period of time, it gained such a reputation that the treaty of Versailles explicitly specified submachine guns among the list of weapons banned from the German military. One of the weaknesses of the MP-18 was its snail-drum magazine, so shortly after World War I, Hugo Schmeisser improved the design to use box magazines. Bergmann continued to make this weapon in secret for a few years after World War I ended and about 25,000 (or 35,000 depending on who you ask) were made in total. However, since Bergmann could no longer manufacture these weapons openly, they finally sold the improved design to the Swiss company SIG (Schweitzerische Industrie-Gesellschaft) in 1920, which started to sell the improved design as the Bergmann Submachine Gun. SIG sold Bergmann models of various calibers to several countries, such as China, Japan and Finland, between 1920 and 1927, when they finally stopped making these weapons.

The Finnish army wasn't interested in this weapon initially, but the Finnish Civil Guard (Suojeluskunta) were interested and bought about 1000 Bergmann submachine guns from SIG in the early 1920s. Around this time, a talented Finnish weapon's designer named Aimo Lahti thought the Bergmann was too expensive and the reliability could be improved as well. He made his first prototype in 1921, a model that fired the .32 ACP cartridge and was about 11.8 inches (30 cm.) long and it was handmade by a blacksmith in Viiala. By 1922, he had a real working prototype (M/22) which was built by a factory with machine tools (Leskinen & Kari in Tampere). He tried to get the Finnish military interested in this weapon, but they refused because it wasn't really production-ready yet, but some members of the Keski-Suomi regiment did express interest in it. Therefore, in 1924, Lahti established Konepistooli Oy (Translation: Machine Pistol Corp.) with members of this regiment, Captain V. Korpela, Lt. Y. Koskinen and Lt. L. Boyer-Spoof. (Korpela had to leave the company later, as he was trying to sell the submachine gun to other countries without permission of the other shareholders). 

Lahti continued to make improvements and by 1924, the Finnish Defence Ministry got interested and bought about 100 submachine guns. At this time, Konepistooli Oy needed every sale they could get. By 1926, the M/26 model was introduced, which used a very unique 36-round magazine, that was not used in any weapon before then.

The Suomi M/26 submachine gun. Click on the image to enlarge.

Note the unique curved magazine shape of this weapon. The M/26 cost about half the price of the Bergmann, but it did not sell well. It also had some feeding issues and shared some of the weaknesses of the original MP-18 and Bergmann. The stock was also not strong enough for military use. Lahti succeeded in fixing these issues in his new model, the M/31.

One of the improvements in the M/31 was to remove the excess room in front of the bolt (which sometimes caused cartridges to turn sideways during loading) to prevent jamming problems. A quick release mechanism allowed the barrel to be rapidly replaced. An improved muzzle brake reduced the muzzle climb during shooting in automatic mode. The most important change was the cartridge used, as the M/31 was designed to use the 9x19 mm. parabellum cartridge that many other countries were using at that time. Because of the 9x19 mm. cartridge, two new magazines, a 20 round box magazine and a 40 round drum magazine were developed as well.

The Finnish Defence Ministry were very interested in the M/31, but Konepistooli Oy lacked the facilities for mass production. Luckily, an engineer named Oscar Ostman was a personal friend of Aimo Lahti. Ostman was the CEO of a Finnish company called Tikkakoski Rauta ja Puuteollisuusyhtio (Translation: Tikkakoski Iron and Wood Products Ltd.), which originally was a metal workshop, but also had experience in making firearm parts (like barrels for rifles and machine guns) for the Finnish military. Interestingly, the major shareholder of Tikkakoski was a German weapons dealer named Willi Daugs. Tikkakoski bought the rights to produce the M/31 from Konepistooli and called it the Suomi KP/-31 (KP standing for Konepistooli (i.e. Machine Pistol) and 31, since it was manufactured in 1931). 

The Suomi KP/-31 submachine gun. Click on the image to enlarge.

Image licensed under Creative Commons Attribution-Share Alike 3.0 Unported license by Mbeesb

The 20 round box magazine could actually be filled with upto 25 cartridges, but it wasn't too reliable when it was filled with 25 cartridges and it was felt that 20 rounds was too little capacity for the magazine and so, the manufacture of these stopped by 1939. The 40 round drum magazine also had some reliability issues, but its bigger problem was loading it -- cartridges had to be inserted into the drum with the cartridges standing on the tips of the bullets. The slightest vibration could cause the cartridges to fall on their sides inside the magazine and the user would have to dump all the cartridges out and start from the beginning again. Luckily, Lt. Y. Koskinen, who was one of the other founders of Konepistooli Oy, came up with the design of an improved 71 round drum magazine, without Aimo Lahti's finding out until it was ready for production. This 71-round magazine was the most well known and successful magazine design of the KP/-31. In fact, the Soviets were so impressed by it, that they cloned it for their PPSh-41, as we saw in the previous article. A 50 round quadruple column casket box magazine of Swedish design was also made for the KP/-31, but this magazine proved vulnerable to small dents and therefore, it was mostly issued with the 71 round drum magazine.

When the Winter War started, Finland only had about 4000 of these in service, but after the Winter War ended and as the Continuation war started, production had ramped up to about 1400-1500 weapons made per month. Finnish soldiers used this weapon with deadly effect against the Soviets. This weapon showed what a useful weapon the submachine gun was to modern armies and other military forces were quick to adopt this concept as well.

The KP/-31 had a number of interesting features about it. It was a blowback action using Advanced Primer Ignition. This means the firing pin ignites the primer of the cartridge, before the bolt stops into battery. The bolt's momentum keeps the cartridge case locked in the chamber until the peak chamber pressure from the gases has dropped to a safe level. Unlike later submachine gun designs, this was largely built by machining the components and therefore took longer to manufacture. For instance, the receiver was machined from a solid forged steel block. The steel used for the barrel and receiver was the best Swedish made chromium-nickel steel that was available during that time. Some of the original barrels for the pre-1931 models were made by Birmingham Small Arms (BSA) in England, but Tikkakoski started making their own barrels by 1931, and many were also supplied by the precision competition rifle manufacturer, Joonas Matarainen. Interestingly, for a submachine gun, it had a quick-detachable barrel and a barrel jacket, features that are usually only found on heavy machine guns. Also, unusually for a submachine gun, each KP/-31 was supplied with two barrels (primary and spare barrel). Each pair of barrels were machined to a very high degree of precision, so that they both had very similar dispersion and point of impact. This allowed the user to quickly change barrels in the middle of a firefight without needing to adjust the sights afterwards! Even though the weapon had a high rate of fire (around 900 rounds per minute), it was surprisingly well-balanced and controllable. 

How accurate was it, the reader asks? Factory testers would shoot 10 shots at a target in semi-automatic mode, using a simple bench rest and all 10 shots would have to hit the bullseye of the target at 100 meters distance. The following two images show the results of tests conducted by the Finnish Army during official acceptance tests.

Click on the image to enlarge.

The diameter of the center circle (the ten circle) of both targets has a diameter of 4 inches (25 mm.). The shots were made from a distance of 100 meters using a simple bench rest. The left image shows 15 rounds fired at this distance using semi-automatic mode. The right image is using a 50 round magazine fired in a single long burst at the same distance, using full-automatic mode. As you can see, the test in semi-automatic mode has a 1 MOA accuracy (and it wasn't uncommon to get sub MOA groups either). In the right image, it can be seen that 48 out of the 50 shots are within the smallest or second smallest circle.

Unlike most other submachine guns, the sights were adjustable to 500 meters distance, which was a bit optimistic, but the weapon was easily capable of hitting targets at 300 meters distance. It was much more accurate than every other submachine gun of that period (and probably even now). In the dense Finnish forests, the range of the KP/-31 was more than adequate and the large drum magazine and fast rate of fire meant it could spray more lead than practically any other automatic weapon of that time. 

One more interesting feature was the cocking handle (charging handle). It was a non-reciprocating design (i.e.) it does not move back and forth when the gun is fired (similar to that of a bolt-action rifle). The user only pulled it back once after loading a new magazine into the weapon, to cock it initially, and after that the charging handle would not move at all. Because of this feature, it didn't have a bolt handle slot and therefore, was less likely to let mud and snow enter into the firing mechanism, which led to greater reliability.

A couple of variants were made to be used inside bunkers and tanks. These had thinner barrel shrouds and no shoulder stock, using a pistol grip instead. These were designed to be used in enclosed spaces where it was necessary to fire through narrow slits. On these variants, the sights located on the left side of the weapon, to make it easier to aim through a slit. The tank version was designed with a special barrel shroud that was permanently attached to the firing port of a 6-ton Vickers tank (the T-26E model). If it became necessary for the crew to abandon the tank, the weapon could be easily removed from the firing port and normal barrel shroud attached to it to use as a regular submachine gun.

One more variant was from 1942. This variant had an "improvement" to add a muzzle brake. This model was called the KP/-31 SJR (SJR from the word "suujarru", the Finnish word for "muzzle brake" or "compensator"). This increased the length of the weapon by 55 mm. Aimo Lahti didn't like the new compensator because the oblique front end of the barrel jacket was found to be as efficient as the compensator. On the other hand, the compensator caused trouble in cold frosty weather, as powder and primer residue would get trapped in the chamber and the resulting sticky mass of condensed water, carbon and salts would stick to the breech bolt and cause misfires. On top of that, the compensator reduced the muzzle velocity a bit as well. This "improvement" enraged Aimo Lahti so much that he attempted to find out who was responsible for this change and have him charged in a military court, but to this day, the identity of the genius responsible remains a classified secret!

The Finns used this weapon against Soviet forces with great success and showed the world how submachine guns could be used in warfare by regular troops and not just as defensive weapons by truck drivers and tank crews. 

The Suomi KP/-31 had superior firepower, excellent accuracy and very high reliability. On the downsides were its weight, high production cost and slower production rate. Finnish infantry soldiers liked this weapon a lot. It was also manufactured under license in Sweden, Denmark and Switzerland and also used by other countries such as Norway, Israel, Germany etc. In 1938, the British Army conducted tests on many different submachine gun models and their Ordnance Board concluded that the KP/-31 was the best weapon by far. However, since the Finns were battling the Soviets at that time, the British concluded that they might not be available for purchase and opted for the Thompson submachine gun instead.

Incidentally, Norway used them until the 1980s and the Vatican Swiss Guard used them until the 1970s (as the Swiss made version of the KP/-31, the Hispano Suiza MP43/MP44). The tank version of the KP-31 (which was described 4 paragraphs above) was still in service in Finland through the 1980s, despite the fact that the T-26E tank that it was designed for, was decommissioned by Finland in 1959!

The PPSh-41 Submachine Gun

In our last post, we studied the German MP40 submachine gun, an influential design. In today's post, we will study a submachine gun of Soviet origin, the PPSh-41.

The PPSh-41 derives its name from the Russian name Пистолет-пулемёт Шпагина which is pronounced as Pistolet-Pulemyot Shpagina (i.e. "Shpagin Machine Pistol"). Shpagin refers to the designer of this weapon, Georgy Semyonovich Shpagin. The number -41 refers to the year that this weapon was first produced.

A PPSh-41 with a drum magazine. Click on the image to enlarge.

Image released under a Creative Commons Attribution-Share Alike 3.0 Unported license by Lposka

The gun was called the "Peh-Peh-Sha" (after the Russian pronunciation of the first letter of each word), or sometimes as "Papasha" (the Russian word for "Daddy"). During the Korean war, US and UK forces who encountered this in the hands of North Koreans and Chinese troops, nicknamed this the "burp gun" on account of the "brrrap" sound it produces when firing in automatic mode.

The origins of this weapon have to do with two reasons. First, when the Soviets fought against Finland in the Winter War of 1939-40, they found that Finnish forces armed with Suomi KP-31 submachine guns could take on superior numbers of Soviet forces fighting with bolt-action Mosin-Nagant rifles at close quarters. The Soviets already had a submachine gun of their own, the PPD-34, but it was hard to produce economically and quickly. Many of the metal parts of the PPD-34 were produced by milling and machining operations, which made it take a long time to produce.

Then, in the summer of June 1941, the Germans launched Operation Barbarossa and invaded the Soviet Union. A large number of Soviet small arms as well as a number of the factories capable of manufacturing small arms, fell into German hands. The Soviets needed a weapon that could be produced quickly and without the use of sophisticated manufacturing technologies.

Enter Georgy Shpagin, a son of a Russian peasant, who had started off life as a carpenter, before being drafted into the Russian army and becoming a gunsmith and later a weapon designer. He took the PPD-40 (an improved version of the PPD-34) as the starting point of his design. While the PPD-40 used mostly machined parts, his new PPSh-41 design largely relied on stamped steel parts. Most of these parts could be manufactured by unskilled workers using equipment that is commonly seen in small workshops and automobile repair garages. Parts were joined together by welding. The PPSh-41 design used less parts than the PPD-40 and could be manufactured in about half the time it took to make a PPD-40. Only the barrel needed a little more sophisticated factory equipment to manufacture and even this was simplified, as will be discussed shortly.

The cartridge used for his weapon design was the 7.62x25 mm. Tokarev pistol cartridge, which was already in service with Soviet forces for some years previously. To simplify the production of barrels, he often used existing barrels designed for the Mosin-Nagant M1891 rifle, which were already bored for 7.62 mm. A single long M1891 barrel would be cut into two shorter barrels for the PPSh-41 as they both use 7.62 mm. diameter cartridges, and then each shorter barrel would have a chamber machined to accept the 7.62x25 mm. Tokarev cartridge. The barrels were chrome lined for extra reliability, but most of the other parts were much more cheaply produced.

The weapon itself fires from an open bolt using the blowback action (similar to all the designs we studied in the last few posts). Earlier models had a selector lever to select the firing mode and later models were designed to fire in full automatic mode only. The firing rate of this weapon is about 1000 rounds per minute, which is the highest of all the submachine guns during World War II. The receiver is hinged to make disassembly and cleaning the weapon in the field easy to do. The chrome lining in the barrel enables it to use corrosive ammunition and not be cleaned for a while in the field.

The first prototypes went into production in November 1941 and by the spring of 1942, the factories were making them at an incredible rate of 3000 per day and by the end of 1942, over 1.5 million of these were made.

Initially, the PPSh-41 was designed to use a drum magazine of 71 round capacity, which was an exact copy of the Finnish Suomi KP-31 submachine gun that the Soviets had encountered in the Winter War. The drum had a spring loaded feed mechanism that the user would have to wind up like a watch to use. However, the drum magazine had reliability issues if it was loaded to its full capacity of 71 rounds and therefore, users would often load less than 64 or 65 rounds to avoid this problem. The drum magazine was also made of a thin sheet metal of 0.5 mm. thickness. This meant that it was pretty easy to bend, which could also cause feed failures. Also, the springs inside the drum magazines would often weaken after a while and make feeding unreliable. On top of that, it took a long time to load a drum magazine. Therefore, newer versions of the PPSh-41 were supplied with 35 round box magazine instead, after about 1942.

A PPSh-41 with a box magazine. Click on the image to enlarge.

The box magazines were easy to carry around in pouches and more reliable than the drum magazines. The thickness of the metal used to make magazines (both box and drum magazines) was later changed from 0.5 mm to 1 mm., which made them much harder to bend accidentally. Many infantrymen would carry one drum magazine in the gun and several box magazines in pouches.

The Soviets made about 6 million of these weapons by the end of World War II. Some of these were later gifted to other communist countries and some African countries. The design of the PPSh-41 was also shared with some countries, most notably, the North Koreans and the Chinese, who made their own versions of this weapon during the Korean war. The Chinese also gave their design to the Vietnamese, who made their own version during the Vietnam war. US and UN troops who faced this weapon in Korea and Vietnam nicknamed this the "burp gun" on account of the noise it made when firing. The weapon still remains in use by some irregular forces around the world.

The MP40 submachine gun

In our last post, we studied about the German MP38 submachine gun. In today's post, we will study its successor, the MP40 submachine gun.

The MP38 submachine gun was a pretty successful design and performed the tasks that it was designed for well. However, it could not be manufactured quickly because of the way that some of the parts were made (many parts were machined). The original manufacturer of the MP38, Erma, gave the design to C.P. Haenel to help with production, but even these two companies together could not meet the demand for these weapons from the German Army. As a matter of fact, they could not even meet their own production targets that they had set themselves! By 1939, the German War Office asked for changes in the production methods to speed up manufacturing.

Both Erma and Haenel were relatively smaller arms manufacturing companies, so larger companies, such as Krupp, Steyr and Merz Werke, were recruited to help. The engineers from these larger companies were experienced in modern mass production technologies and they made changes to the MP38 model to speed up its production rate. The new model was introduced in 1940 and was called the MP40.

A MP40 with the stock folded. Click on the image to enlarge.

Image licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license

A MP40 with the stock extended. Click on the image to enlarge

Image licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license

In the MP38, many parts were machined, which made the process of manufacturing expensive and slow. In particular, the receiver took multiple machining operations on a block of steel, to make the final product. Many of the parts of the MP40, on the other hand, was made by stamping out steel parts using dies and high speed presses and then joining the parts together by using brazing and spot-welding techniques. Only the barrel and the bolt were machined in the MP40. This made the production rate much faster. Over 1.1 million MP40 submachine guns were produced between 1940 and 1945.

Therefore, the MP38 was one of the last submachine guns to be largely manufactured with machining technologies and the MP40 was one of the first submachine guns designed specifically to be manufactured quickly and cheaply. This is why the quality and finish of the MP38 is usually superior to the MP40, but the MP40 is just as effective as the MP38.

One weakness of the MP40 is that it uses the same double-column single-feed magazines as the MP38 and therefore, it has the same issues with dirt and jamming.

The MP40 comes in multiple variants as the Germans continued to improve the design to reduce the manufacturing time. Erma, Haenel and Steyr were the main manufacturers and a number of the parts were made by other subcontractors. For instance, one of the manufacturers of the plastic grips was the German electrical giant AEG (these days, they are known as AEG/Electrolux). Krupp and Merz Werke produced a lot of the stamped parts (tubes, frames etc.) for both Erma and Haenel (Steyr produced their own stampings), Mauser Werke supplied barrels and so on.

The MP40 is really the prototype for a number of other submachine guns that have been made since. It influenced the development of the US M3 Grease gun and the British Sten gun, as both the US and the UK saw the need for a rapid-firing weapon that could be produced quickly and cheaply. It is one of the first weapons to use plastics instead of wood. The forward folding stock design was first designed for the MP 40 and later copied by other people, notably the AK family.

Interestingly, the MP40 was often referred to by Allied troops as the "schmeisser", named after the famed German designer, Hugo Schmeisser. In reality though, he had very little to do with this design, as most of it was done by Berthold Geipel and Heinrich Vollmer and later improved by mass-production specialist engineers at other companies. About the only contribution of Hugo Schmeisser to the design was the magazine, which Hugo Schmeisser had designed and patented for another weapon, but the German War Office insisted on using Schmeisser's magazine design for the MP38 and MP40. Interestingly, Hugo Schmeisser did design the MP41, which is largely a MP40, but using a wooden stock and a selector lever from the MP-28, which Schmeisser had worked on earlier.

Even though the German factories stopped producing the MP40 after World War II, they remained in service with other countries for several years since. For instance, France used the MP40 during the 1950s and 1960s and Norway still used them until about 1990 or so.

The MP38 Submachine Gun

In our last couple of posts, we traced the development of the American M3 Grease Gun and the British Sten Gun. In today's post, we will study the gun that preceded them both and inspired their creation. Today, we will study about the German MP38 submachine gun.

A MP38 submachine gun. Click on the image to enlarge.

The full name of this weapon is Maschinenpistole 38 (i.e. "Machine Pistol 38"). The origins of this weapon have to do with advancements in military doctrine after World War I. It was during and after this war that military concepts such as tanks, troop carriers, paratroopers etc. started becoming popular. There was need for a rapid firing weapon that could be used from inside vehicles such as tanks and trucks, as well as carried by paratroopers. General infantry crews also had use for a small, light, rapid firing weapon to protect themselves, while transporting their heavier machine guns to other locations. The German Wehrmacht was beginning to develop its theories of lightning warfare (i.e. the Blitzkrieg), where the idea was to use rapidly moving mechanized forces on the ground, operating together with air support. The German Army Weapons Office published a requirement asking for a suitable submachine gun to be designed in 1938.

The German arms company, Erfuter MaschinenFabrik Gmbh, (translation: Erfurt Machine Factory Inc.), better known by its shorter trade name, Erma, began to develop a weapon to meet this requirement. Instead of developing a weapon from scratch, they modified an existing design that they were already working on, the MP36. The MP36 was actually a compact version of the Erma EMP (Erma Maschinen Pistol (translation: Erma Machine Pistol)).

Erma EMP. Click on the image to enlarge.

The Erma EMP was actually developed by Heinrich Vollmer, a German arms designer who had his own small arms manufacturing company. He had designed this gun in 1930, based on an earlier design he had worked on in 1925 and 1928, but his newer design used a side-feeding box magazine (a feature later seen on the Sten and Sterling submachine guns) and a telescoped return spring (a feature used in the MP38 and MP40). However, the German military stopped supporting his company in 1930 and since he didn't have the financial capability to manufacture these, he sold the design and manufacturing rights to Erma, who started producing his design in 1932 as the Erna EMP. Some of these Erma EMP guns were sold to Spain and some South American countries.

The Erma company had started to make a compact version of the EMP, which they called MP36, which was a selective fire weapon. When the requirement came from the German War Office, they took this prototype and simplified it a little more and called in the MP38. One of the requirements was to use plastics in the furniture instead of wood, and the MP38 uses bakelite for its handguards and grips. After the German War Office announced that they had accepted the design, Erma started to produce the weapon in 1938 and a couple of years later, C.G. Haenel also started producing the weapon.

The MP38 uses a blowback action and features a folding butt, which reduces its length considerably when folded. It uses the 9x19 mm. parabellum cartridge, which was also used by the Luger pistol in World War I. All the critical operating parts are contained in the receiver. There is only one mode of fire: full automatic mode. However, due to the slower rate of fire, it is possible to fire single shots by pulling and releasing the trigger quickly. The magazine holds 32 rounds and is a double column, single-feed type. Uniquely, on the underside of the barrel, there is a "lip" or "resting bar". This is designed to keep the weapon steady, when firing over the side of an open-top armored personnel carrier. The idea is that the lip latches on the side of the vehicle's wall and prevents the recoil from driving the weapon back into the vehicle's compartment. A cooling fin at the end of the barrel helps dissipate some of the heat. The pistol grip and handguard are made of bakelite plastic to save weight and this is the first submachine gun in history to feature plastic parts.

Interestingly though, the receiver of this weapon is made of machined steel instead of being stamped. Therefore, it took longer to make the receivers. So while the gun was a success, it could not be made fast enough and production only lasted a couple of years before they developed the MP40 in 1940. The MP40 was made of stamped steel and used spot welding technologies to speed up production. Production of the MP38 did continue until 1941 though.

A weakness of the MP38 and MP40 was the magazine, which tended to be affected by dirt. The same magazine design was copied by the British for their Sten gun, so that they could reuse German magazines and therefore, the Sten gun inherited the same weakness as well.

One more interesting fact is that the Allies incorrectly referred to the MP40 as the Schmeisser, named after the famous German weapons designer, Hugo Schmeisser. In reality, he had very little to do with the design of the MP38 and MP40. If anything, his sole contribution was a patent he held on the magazine, which he had actually designed for a different weapon.

The MP38 may be considered as the one of the last submachine guns that was built out of machined parts. Therefore, it has a better quality and finish, compared to the MP40 that followed it. We will study the MP40 in the next post.

The Sten Gun

In our last post, we saw how America adopted the M3 a.k.a the Grease Gun. In today's post, we will look at one of the guns that inspired it, the British Sten gun. This was a gun that was designed to be manufactured cheaply and easily and we will study its origins and design today.

Different Sten gun models. Click on the image to enlarge.

First, we must go back in history to Europe in the summer of 1940. German soldiers were sweeping through Belgium and France and allied troops were in a desperate situation and trapped in the tiny port of Dunkirk. The British deployed every boat and ship available to rescue the stranded Allies and in nine days (27th May - 4th June), over 300,000 soldiers (British, French, Polish, Belgian, Dutch etc.) were evacuated to England. However, this rapid evacuation also resulted in soldiers leaving their equipment behind and large amounts of firearms fell into the hands of the Germans. Shortly after that, the Battle of Britain started and many factories in England were bombed. As a result of all this, there was a shortage of small arms in Britain. The British were buying Thompson submachine guns from the United States, but the factory could not keep up with the demand (and after 1941, many of those Thompsons went to the US military, so they couldn't supply anyone else anyway). Therefore, a decision was made to design a submachine gun that could be made in England quickly and cheaply.

The task of designing this new weapon fell to Major R.V. Shepherd of the Design Department at the Royal Arsenal, Woolich and Mr. Harold J. Turpin, of the Design Department of the Royal Small Arms Factory, Enfield. The design they came up with was called the STEN. The "S" and "T" in the name came from the first letters of the designers last names (S from Shepherd and T from Turpin) and the "EN" came from the first two letters of "Enfield".

From the beginning, the aim was to design a cheap gun that could be manufactured with a minimum of machining operations. It had to be capable of being manufactured in small workshops and produced as quickly as possible. It also had to be capable of single shot and automatic fire and designed for close range fighting. It was designed to use the 9x19 mm. Parabellum Luger cartridge, which was also used by the Germans. The Sten was also deliberately designed to fit German 9 mm. magazines from the MP-38 and MP-40, so that they could use captured German ammunition and equipment if needed.

The design that they came up with was a submachine gun using a blowback mechanism and firing from an open bolt. When the weapon is cocked, the bolt remains at the rear of the weapon. When the trigger is pulled, the bolt is pushed forward by spring pressure and strips a cartridge from the magazine, chambers it and then fires it. The firing pin is fixed in front of the bolt. After the cartridge discharges, the bolt moves rearward against spring pressure and inertia of the heavy bolt and then recocks itself. The working components of this weapon are housed in a basic tubular metal receiver with a barrel on one end and a wire shoulder support welded to the other end, with a simple trigger mechanism in between

The Sten gun, Mark I

The first version of the Sten gun, the Mark I model, came with a conical flash hider and contained some wooden parts (the foregrip and part of the stock). The front pistol grip could also be rotated to make the firearm smaller and therefore, easier to pack. Production started in late 1940 and about 100,000 of this model were made.

Compared to the Mark I model, the Mark II model was much more stripped down. The flash hider was removed and the folding front pistol grip and all the wood were eliminated as well. This made the Mark II smaller and lighter than the Mark I model.

The Mark II variant was the most commonly manufactured model and about 2 million of these were produced. Some Mark II models were made with integral suppressors attached and were classified as Mark II (S)

The Mark III variant was even more stripped down than the Mark II model and was first produced in 1943. In this model, the receiver and the barrel shroud are made from a single tube, by wrapping a sheet steel plate into a cylindrical shape and welding the top. This model is also a bit lighter than the Mark II model.

The Sten Mark III model was the second most commonly produced model of the Sten gun family and was the most stripped down model of the series, and therefore the lightest version.

By 1944, the threat of a German invasion of Britain was over and the Sten gun quality improved. Models Mark IV and Mark V had better quality fit and finish and even came with wooden parts.

The Sten gun model Mark V

The Mark IV model was a paratrooper's model with a folding stock, but never got off the prototype stage. The Mark V model had better sights and finish and came with a bayonet attachment as well.

The Sten was designed to be manufactured quickly and easily. This is why most of the components could be manufactured by stamping sheet metal and doing some minor welding. From the beginning, many of the parts were subcontracted to small workshops, with final assembly being done at the Enfield factory. This was especially useful as the larger factories were being bombed from the air by the German Air Force, early on during the war. The design was made simpler with each generation and the Mark III model only had 47 parts. Interestingly, one of the largest manufacturers of the Mark III model was a toy company called Lines Brothers. The Sten was really cheap to manufacture and only cost about $10 to make, which was much cheaper than the Thompson submachine gun, which cost about $200 then.

While Sten guns were cheap to manufacture, they occasionally had jamming issues as well. The gun was designed to use the same magazine as the German MP-38/MP-40, so that people could reuse captured equipment. However, it also inherited the problems of the German magazine, in particular dirt could cause it to jam. In the absence of a pistol grip and forward grip in the Mark II and Mark III versions, some soldiers would hold the magazine with the supporting hand, causing it to wear out the magazine catch and cause failure to feed issues. The safety device was rudimentary and there was a danger of accidental discharge upon dropping the weapon, especially since many were crudely made. The Mark V model attempted to fix some of these issues.

The Sten was loved and hated by its users at the same time. Many didn't like its peculiar appearance and reliability (at least for the Mark II and Mark III models) and it was nicknamed the "Plumber's Nightmare" and the "Stench Gun". However, they liked its cheap cost and short range firepower. It was manufactured during World War II by many British companies, as well as workshops and factories in Canada, Australia, France, Poland, Denmark, Norway etc. It was responsible for the US manufacturing its own cheap submachine gun model: the M3 grease gun. Towards the end of World War II, even the Germans got in the act and made over 28,000 copies of the Sten gun. After World War II, many were made in small workshops Israel in 1948. The Sten gun is still in use in some countries around the world.

The M3 Grease Gun

In today's post, we will study a submachine gun that was in US service for 50 years and is still used by some military forces elsewhere in the world. Today's post will study about the famous M3 and M3A1 submachine guns, more popularly known as "grease guns".

The origin of this design has to do with the onset of World War II. In Europe, the Germans had developed the MP-40 submachine gun and the British had the Sten submachine gun. Both these weapons were chambered to fire the reliable 9x19 mm. Luger cartridge. In 1941, the US Army Ordnance Board conducted some studies on the effectiveness of these weapons on the battlefield and determined that there was a need for similar weapons for the US military as well. At that time, the US military had already adopted the Thompson submachine guns (which were developed at the end of World War I) into service in 1938, but the Tommy guns were relatively expensive to manufacture. The Ordnance Board wanted a weapon that could fire the same .45 ACP cartridge of the Thompson, but which could be manufactured much cheaper and could be fired as accurately as well.

The final list of requirements included:

1. Weapon to be made of metal completely, with largely sheet metal construction, in order to speed up manufacturing.
2. Weapon designed to fire .45 ACP cartridges, since the US military was already using this cartridge (The Germans and British were using 9 mm. Luger cartridges for their submachine guns)
3. Weapon to be designed for fast production, with a minimum of machining operations.
4. Weapon to be designed to be cheap to manufacture (cheaper than the Thompson submachine gun)
5. Weapon to be designed as reasonably accurate. It was required to demonstrate that this weapon could put 90% of shots fired in a standing position in full-automatic mode into a 6x6 foot target at a distance of 50 yards. 
6. Weapon to be capable of firing in both semi-automatic and full-automatic modes. This requirement was later removed during development of the weapon and it was designed to fire full automatic only.

The task of designing this weapon fell to George Hyde of General Motors' Inland Division. George Hyde was actually of German descent and had emigrated to the US in 1927, whereupon he changed the spelling of his last name from "Heide" to "Hyde". He was a well known gun designer in 1941 and was put in charge of designing the new weapon. Meanwhile, another engineer named Frederick Sampson was put in charge of preparing the tooling for mass production of this weapon. During the design phase, a conversion kit was also designed, which would allow the user to quickly convert the gun from firing .45 ACP to firing the 9 mm. Luger cartridge.

The prototypes were completed in late 1942 and approved for mass production. The Guide Lamp division of General Motors (the same people that manufactured the FP-45 Liberator pistol) was put in charge of manufacturing it. While the weapon was given the official designation of "U.S. Submachine Gun, Caliber .45, M3", many people noticed that it resembled grease guns used by automobile mechanics and therefore, the new weapon was nicknamed the "Grease Gun".

The M3 Grease Gun. Click on the image to enlarge.

Image licensed under the Creative Commons Share-Alike 3.0 Unported license by Curiosandrelics

The M3 was designed to be cheap. The manufacturing cost of one of these in World War II was around $18. Only three parts, the bolt, the barrel and the firing mechanism, were precisely machined. Most of the other parts of this gun were manufactured by using metal stamping and pressing technologies. Spot welding and seam welding were used to join most of the parts together and some other parts were riveted together. These processes allowed the gun to be manufactured very rapidly and with low cost. The stock was simply made from a single steel rod, which was bent into shape. The ends of the stock were drilled and tapped, so that it could be used as a cleaning rod, as well as a disassembly tool. In the M3A1 model, the stock also had a tool welded to it, to be used to load a magazine. The safety was a projection on the inside of the ejection port dust cover, which locked the bolt into the forward or rear positions. However, since the metal around the dust cover was so thin, it could get bent easily and the safety mechanism wouldn't work any more.

The two halves of the receiver were made by stamping sheet steel and then the two halves were welded together. The bolt was made heavy and made to run on two parallel guide rods, which had twin return springs. This allowed the receiver to be made to looser tolerances. The barrel was cold swaged to save time and cost. The weapon was designed to be striker fired, with a fixed firing pin inside the bolt.

When the M3 first entered service, no replacement parts were supplied. The weapon was originally intended to be a low-cost tool that could be discarded when it ceased working. However, due to a temporary shortage of M3s in the middle of 1944, the US Army Ordnance workshops manufactured some spare parts to keep existing weapons operational. There were also a number of issues with the M3 and several improvements were incorporated into the M3A1 model, which went into service in December 1944. During the Korean war, existing M3 guns were converted to the M3A1 standard.

While it was hoped that this gun would be produced in large numbers to replace the Thompson submachine gun in US service, this did not happen and there were about three times as many Tommy guns in service than M3/M3A1 at the end of World War II.

Due to its cheap cost and portability of the weapon, it was issued to paratroopers, tank crews and truck drivers. Even though it was withdrawn from frontline service in the US military in 1957, they were still issued to tank and truck drivers and were carried by US tanks during the 1991 Gulf war. The M3A1s were finally replaced starting in 1992, with the M4 carbine. That means it served in the US military for 50 years (1942 - 1992). It is still used by military forces in other parts of the world.

Machine Guns - General

In our last few posts, we studied different feed systems such as ammunition belts, chain feeds and feed strips. All these mechanisms are generally used with machine guns. Therefore, in the next series of posts, we will study all about machine guns.

A machine gun is a firearm that is capable of fully automatic fire. What this means is that as long as the firearm has ammunition available to it and the trigger is pulled, it will continue to load and fire ammunition automatically. Machine guns are capable of firing at high rates of several hundred rounds per minute and are designed to keep firing for considerable periods of time. The capability of maintaining sustained fire for long periods of time is what distinguishes a machine gun from an automatic rifle or an assault rifle (both of which can fire on full-auto only for limited periods of time).

US military doctrine has another interesting way of classifying automatic rifles versus machine guns. If the fully automatic firearm is operated by a crew, then it is a machine gun, but if a fully automatic firearm is operated by a single person, then it is an automatic rifle. In many cases, weapons fall exclusively into one of these two designations, however, we have one major oddball that falls into both categories -- the M249. US Army Field Manual FM 3-22.68 ("Crew-Served Machine Guns") describes the M249 as both an automatic rifle and a machine gun! Quoting from the manual chapter 4, section 5, paragraph 4-207, "Both the M249 automatic rifle and the M249 machine gun are identical, but its employment is different. The M249 automatic rifle is operated by an automatic rifleman, but its ammunition may be carried by other Soldiers within the squad or unit. The M249 machine gun is a crew-served weapon."

Machine guns can be portable as well as mounted and therefore, they are generally classified based upon size.

Before we dig deep into the topic, let us talk about submachine guns, which are portable firearms that are designed to fire pistol-sized ammunition. While they have a high rate of fire, some authorities do not consider these as "true machine guns" as they are not capable of sustained fire for long periods of time. Examples of these would be the Thompson submachine gun (which actually coined the term "submachine gun") also known as the Tommy gun, Chicago typewriter, Trench broom etc., Heckler & Koch MP5, Uzi etc. All these weapons are designed to fire pistol sized ammunition such as .45 ACP, 9 mm Parabellum etc.

Next, we have true machine guns like the Light machine gun, Medium machine gun, Heavy machine gun, General purpose machine gun which all use larger ammunition calibers (rifle calibers or larger). These weapons are generally heavier than other automatic weapons (even the "light" machine gun is heavier than an assault rifle, for instance). Examples of these would be the Lewis gun, the Bren gun, MG-34, Browning M1917, Browning M2, M60 etc.

A Lewis gun. Click on the image to enlarge. Public domain image. 

A M60 machine gun. Click on the image to enlarge. Public domain image.

We will study more into these various types of machine guns in the following posts.

Finally, we have weapons in the autocannon category. The difference between an autocannon and a machine gun has largely to do with the type and size of ammunition. If the firearm uses ammunition greater than 16 mm. diameter, or if it uses large caliber explosive rounds, then it is considered an autocannon rather than a machine gun. Examples of an autocannons include the M242 Bushmaster (which we studied briefly, when recently studying about chain guns), Oerlikon 20 mm. autocannon etc.

Since machine guns are designed to fire on automatic for longer periods of time, they tend to overheat quickly. Hence, many of them are either designed to have a built in barrel cooling system or feature a quick-change barrel replacement system. For the same reason, most machine guns are also designed to fire from an open-bolt, so that the breech area can be more efficiently air-cooled when the gun is not firing.

In the next few posts, we will study all about various types of machine guns and their history.