M/29s were in Norwegian service by the time of the 9 April 1940 German invasion. The M/29 saw service in the 1940 Norwegian Campaign, often deployed as the only heavy weapon of Norwegian front line units. Commercial variants Colt commercially produced the M1917 under several names: Colt Model of 1919 (not to be confused with the air-cooled M1919 Browning machine gun) Colt Model of 1924. Colt Model of 1928. The Model 1928 featured a thumb safety, Type A flash hider, and a mount for a panoramic sight unit. Colt MG38 series, derivatives of the Colt M1928 for general commercial sale, designed in 1931. The 38 and 38B were water-cooled with a barrel jacket threaded inside the trunnion, unlike the M1917 and Colt Model 1928. The 38BT was a short heavy barreled air-cooled weapon resembling the Browning M1919A2, designed for use in tanks. The MG40 was an aircraft machine gun, with double handgrips. The 38 series also features spade grips, not found on the rest of the M1917 and the majority of the M1919 families. Derivatives A simplified, air-cooled version of the weapon, the Model 1919, was adopted after World War I and saw action in World War II, the Korean War, the Vietnam War, and the Congo crisis. Users : Colt Model 1928 and FN Model 30 in 7.65×53mm Mauser : locally produced : bought 256 MG38s between 1920 and 1938 and 207 MG40s in 1933-1934, all in 7.65×53mm Mauser. : "Type Triple-Ten" aka "Type 30", a chinese copy of the M1917 in 7.92×57mm Mauser used in the Second Sino-Japanese war : used airborne variant in 7.5×54mm as the Modèle 1938. The M1917 HMG was also used by the BF-ONU and during the First Indochina War. : FN30 variant in 6.5×54mm Mannlicher–Schönauer : Model 1924 in 7×57mm Mauser : The Armed Forces received 316 M1917A1s before the Korean War, and 751 were in service with the Army by the end of the war. : Model 1919 in 7×57mm Mauser : m/29 : bought 144 MG38s between 1928 and 1934 (designated as Kulspruta (Ksp) m/36) : FN Model 30 in 8x52mmR, designated as the Type 66 : Acquired through Lend-Lease : was the standard medium machine gun until it was replaced a few years after WWII. It was used in the Army Reserves and Army National Guard until the late 1960s and early 1970s. See also List of U.S. Army weapons