The MP34 was based on a design for the MP18 by the Rheinmetall company based in Düsseldorf. The weapon is similar in design to the MP18 Bergmann, which itself saw service towards the end of the World War I. Restrictions on the manufacture of certain armaments within the 1919 Treaty of Versailles forbade Germany from manufacturing certain types of weapons, such as light automatic firearms (designated as SMGs with barrels in excess of four inches and magazines holding more than eight rounds). To circumvent the treaty, Rheinmetall acquired the Swiss company Waffenfabrik Solothurn in 1929 and began secret production of a prototype. What was to become the MP34 was originally designated ‘S1-100’ using the company’s standard naming convention. Due to the Solothurn company being unsuited for mass production, Rheinmetall took a controlling interest in Waffenfabrik Steyr, an established arms manufacturer in Austria. Weapons manufactured by Steyr were sold via the Zurich-based trade company Steyr-Solothurn Waffen AG to both the commercial and military markets. The MP34 was manufactured from the very best materials available and finished to the highest possible standard. It was so well manufactured that it has often been nicknamed the "Rolls Royce of submachine guns". However, its production costs were extremely high as a consequence. Portugal purchased small quantities of the S1-100 in 7.65 mm Luger calibre in 1938, and the weapon was adopted as the m/938 submachine gun. In 1941 and 1942, larger numbers of 9mm MP34 guns were delivered to Portugal by Germany. In Portuguese service, the 9mm MP34 was known as the m/942. Many m/942 guns carry a Portuguese crest just forward of the safety mechanism in combination with Waffenamt (WaA) markings. The m/942 remained in service with Portuguese Army into the 1950s, and was used until the 1970s by paramilitary and security forces in Portugal's overseas African colonies during the Portuguese Colonial Wars. This example is a 1942 Portuguese Export.
Marks and Stamps: Top of Receiver) German Nazi Waffenamt proof mark Portugal crest 1942 Steyr Trademark (L side of receiver and stock) Serial no.| Accession Number: 311 | Period of Use: 1930-1970s |
| Type: Machine pistol/SMG | War Zones: |
| Country of Origin: Austria | Type Date: 1930 |
| Manufacturer: Waffenfabrik Steyr | Serial Number: 3930 |
| Manufacture Date: Unknown | Calibre/Ammunition: 9mm |
| Weight: 3870g | Length Overall: 851mm |
| Cyclic Rate: 500rpm | Length Barrel: 196mm |
| Deactivation Certificate Number: CG 7632 |