Erma EMP The German sub - machine gun EMP ( " Erma Maschinenpistole " ) also known as MPE ( Maschinenpistole Erma ) was produced by Erma factory was based on designs acquired from Heinrich Vollmer . The gun was produced from 1931 to 1938 in roughly 10 , 000 exemplars ( in three main variants ) and exported to Spain , Mexico , China and Yugoslavia , but also used domestically by the SS . It was produced under license in Spain by the arsenal of A Coruña under the designation M41 / 44 . History . In the early 1920s , Vollmer started to develop his own sub - machineguns . His early models , named VPG , VPGa , VPF and VMP1925 were fairly similar to the MP18 . The VMP1925 had a wooden handgrip and was fed by a small 25 - round drum magazine , connected directly to the gun . The VMP1925 was secretly tested by the Reichswehr , along with competing designs from Schmeisser and Rheinmetall . ( The Reichswehr was prohibited by the Versailles Treaty from having sub - machine guns in service , although the German police was allowed to carry a small number . ) Secret funding was given to Vollmer to continue development , and this resulted in the VMP1926 , which mostly differed from its predecessor by the removal of the cooling jacket . A subsequent development was the VMP1928 , which introduced a 32 - round box magazine sticking from the left side . The final development of this series was the VMP1930 . ( It can also be seen at the WTS . ) This model introduced a substantive innovation — a telescoping main spring assembly , which made the gun more reliable and easier to assemble and disassemble in the field . Vollemer applied for a patent for his innovation in 1930 and it was granted in 1933 as DRP # 580620 . His company , Vollmer Werke , produced however only about 400 of these , and most were sold to Bulgaria . In late 1930 , the Reichswehr stopped supporting Vollmer financially ; consequently he sold the rights to all his designs to the company known as Erma Werke ( which is an abbreviation for Erfurter Machinenfabrik , Berthold Geipel GmbH ) . The sumbachine guns that Erma started to sell in 1932 under the names EMP ( Erma Machinenpistole ) or MPE ( Machinenpistole Erma ) was basically just the VMP1930 with the cooling jacket restored . Although there were several variants with varying barrel lengths and sights made to customers ' specifications , roughly three main variants were produced : one with a 30 cm barrel , tangent rear sight and bayonet lug was apparently sold to Bulgaria or Yugoslavia . The second model , sometimes called the MP34 , or the " standard model " , had a 25 cm barrel and no provision for a bayonet ; the rear sight on these varies — some had a tangent sight , others a simplified flip - up " L " sight . A third variant was basically similar in the metallic parts , but replaced the foregrip with a MP18 - style stock with finger - grooves . Overall , at least 10 , 000 of these Vollmer - based designs were made by Erma . They were adopted by the SS in 1936 , but also sold to South - American countries and to Spain , were it was subsequently manufactured locally under the designation M41 / 44 . In the Spring of 1939 , a large number of defeated Spanish Republicans fled to France , where they were disarmed . Some 3 , 250 EMPs formerly in the possession of these fighters ended up in a French warehouse at Clermont - Ferrand . The EMPs were usually referred to as the " Erma – Vollmer " in French documents . The French tested the weapons and decided to adopt them for their own service . A provisional manual was printed in French as " Provisoire sur le pistolet - mitrailleur Erma – Vollmer de 9mm " , issued on December 26 , 1939 and updated in January 6 , 1940 . However , the French had obtained only some 1 , 540 suitable magazines for these guns , so only 700 - 800 EMPs were actually distributed to the French forces , mostly to the Mobile Gendarmerie . After the Nazi conquered France , some EMPs armed the Legion of French Volunteers Against Bolshevism , which eventually became part of the SS Charlemagne division . This division was practically destroyed in February 1945 in Eastern Prussia , now part of Poland . Numerous EMPs have been found in the last - stand battlefields of the SS Charlemagne division ; most of these guns lack any German military stamps or marks . The EMPs which arrived in German hands via the French route were given the ( fremden Geräts ) designation 740 ( f ) . In Francoist Spain , the EMP was produced chambered in the 9mm Largo cartridge . It was informally known as " subfusil [ modello ] Coruña " . Design . Its arming lever is on the right . The magazine housing , which is on the left , is slightly canted forwards to assist in feeding ammunition . The weapon could be fired either in semi - automatic or fully automatic modes . Influence . The final development at Erma is known as the EMP 36 . This can be considered an intermediate model between the EMP and the MP38 . Although many details of the mechanism were changed from the EMP , it retained Vollmer ' s telescoping main operating spring basically unchanged . On the exterior , the most obvious differences are that the magazine housing was now almost vertical , although still canted slightly to the left and forward . The solid wood stock was replaced with a wood frame and a folding metal butt . It is not entirely clearly who designed the EMP 36 , although Berthold Geipel himself is usually credited . Apparently , the features of the new design were the result of another secret contract with the German army . The EMP ' s telescopic cylinder return spring guide was retained for the Maschinenpistole 38 .