Monday, September 21, 2015

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.


  1. How was the magazine affected by dirt?

    1. Hi Richard,
      The problem was that the magazine was designed to hold cartridges in a double-column, except at the lips, where they merge into a single column before feeding out. This causes extra friction to the cartridges inside the mag, which sometimes causes failure to feed. The presence of a little bit of dirt in the magazine makes it even more likely to cause feed failures.

      The Editor

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