The Degtyaryov machine gun ( literally: "Degtyaryov's infantry machine gun") or DP-27/DP-28 is a light machine gun firing the 7.62×54mmR cartridge that was primarily used by the Soviet Union, with service trials starting in 1927, followed by general deployment in 1928. Besides being the standard Soviet infantry light machine gun (LMG) during World War II, with various modifications it was used in aircraft as a flexible defensive weapon, and it equipped almost all Soviet tanks in WWII as either a flexible bow machine gun or a co-axial machine gun controlled by the gunner. It was improved in 1943 producing the DPM, but it was replaced in 1946 with the RP-46 which improved on the basic DP design by converting it to use belt feed. The DP machine gun was supplemented in the 1950s by the more modern RPD machine gun and entirely replaced in Soviet service by the general purpose PK machine gun in the 1960s. Design The DP-27 is a light machine gun designed for the Soviet Red Army in the 1920s under the leadership of Vasily Degtyaryov (1880-1949), the first test model being the DP-26. Two test guns were manufactured and fired 5,000 rounds each from September 27–29, 1926, during which weaknesses were discovered in the extractor and firing pin mechanisms. After design improvements, two more guns were made and tested in December 1926, firing 40,000 rounds under adverse conditions, resulting in only .6% stoppages. However, changes to the bolt carrier and the chamber locking mechanism were still required. After this redesign the improved gun, now called the DP-27, was tested by the Red Army at the Kovrov plant on January 17–21 of 1927, passing all tests and being approved for manufacture. A full year of service testing followed, after which the primary requested change was the addition of the large flash suppressor that is now considered one of the recognition features of the design. With further refinements, the DP was to be the primary light machine gun of the Red Army during WWII. The DP-27 was designed to fire the same 7.62×54mmR (R indicating rimmed) ammunition as the main Soviet infantry rifle, the Mosin-Nagant, much simplifying ammunition logistics for Soviet infantry units. Of typical Russian design philosophy, the DP-27 was a sturdy and simple gun that was easy and cheap to manufacture, and could be relied upon to perform even in the most adverse conditions; it was