Degtyarev’s PPD-40 was the first submachine gun adopted in a large scale by the Soviet Union. Its development began in 1929 with a locked breech gun modeled after Degtyarev’s DP light machine gun, but evolved into a much simpler blowback system. It was accepted as the best performing gun of 14 different submissions in Soviet trials of 1931/2, and first entered production in 1934. In this form, it used a 25 round curved stick magazine, and was chambered for the 7.62x25mm cartridge. In 1938 Degtyarev made a number of changes, most importantly developing a drum magazine based on the Finnish Suomi m31 drum. The PPD-38 drum had a short section of feed tower to allow the gun to use either drums or stick magazines, and this was dropped with the final iteration in 1940 when the gun was agains changed, this time to accept only 71 round drum magazines of the m31 type.
The PPD-40 finally entered serious production in 1940, with just over 81,000 made. This production would continue into early 1941 with another roughly 6,000 made before it was replaced by the faster to produce PPSh-41 submachine gun. The PPD-40 was a relatively heavy SMG at 12 pounds (5.45 kg) unloaded, and with a rate of fire of approximately 900 rounds per minute. This particular example was captured and used by the Finnish military, and appears to have a PPD38 bolt in it.