The MP32 (also known as the Bergmann Machine Pistol 32 or BMP32) was designed by Emil Bergmann, son of noted German designer Theodore Bergmann. The first batch of guns were made by the Danish firm Shulz & Larsen, and adopted by the Danish military (in 9mm Bergmann caliber, matching their Bergmann M1910/21 handguns). Bergmann improved the design and introduced the MP34 in 1934, and this model was ordered in large numbers by Germany and manufactured Junker & Ruh (after Walther declined a contract to build them on account of massive PPK orders). Further improvements to allow better mass production were introduced as the MP35 and MP35/I.
The Bergmann MP32 has several feature that distinguish it from other guns of the time. First, it uses a magazine mounted on the right side of the receiver, and ejects our the left side (the reverse is much more common on submachine guns). Second, it has a a bolt handle located at the very back end of the receiver, which is rotated up to the vertical position and pulled back to operate (similar to the Hotchkiss Portative). Thirdly, it has a trigger that appears to be skeletonized.
The trigger mechanism of the MP32 allowed the shooter to fire single shots by pulling the trigger partway back, and full auto fire by pulling the trigger fully to the rear. On the original MP32 version, the safety was located at the rear of the receiver, to be operated by the firing hand. In later refinements (the MP34 and MP35) the safety was moved up to the side of the action, to be operated by the support hand. In addition, the MP32 used a proprietary box magazine (32 round capacity), which would be replaced by standard Schmeisser MP28 mags on later variants. Two barrel lengths were available from the factory, a 200mm and a longer 320mm with a bayonet lug.
In addition to an original German-language MP32 manual, we have a series of 1933 and 1934 dated reports from German testing of the MP32 and MP34 prior to large German orders for the guns: