 Complete the following phrase:  DS-39  was a Soviet medium machine gun, designed by Vasily Degtyaryov, that was used during the Second World War. The work on the guns design began in 1930, and it was accepted by the Red Army in September, 1939. About 10,000 were made from 1939 to 1941, but the weapon was not successful in service and its production was discontinued after the 