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.