The 7.92×107mm DS was a Polish 7.92 mm anti-tank ammunition designed specifically for use with the karabin przeciwpancerny wz.35 anti-tank rifle. It was based on a standard 7.92×57mm Mauser cartridge, but was much longer (107 mm as opposed to the 57 mm of Mauser cartridge) and was modified to provide higher muzzle velocity and hence more penetrating power. History In the late 1920s, the Polish General Staff started the development of a light anti-tank weapon for the Polish infantry. In 1931, Lt. Colonel Tadeusz Felsztyn from the Institute of Armament Technology in Warsaw started the first tests of various low-calibre cartridges. After the tests of German-made Hagler bullets proved the possibilities of such ammunition in perforation of steel plates, the National Ammunition Factory in Skarżysko-Kamienna was ordered to develop its own 7.92 mm cartridge with a muzzle velocity of over . After a series of tests, a new DS cartridge was proposed. The DS ammunition was based on a standard 7.92 mm cartridge used by both the Mauser rifles and the Polish Karabinek wz. 29. The length of the cartridge was extended to and the overall weight reached . After an additional series of tests, the initial copper coating was replaced with a coating made of brass (an alloy of 67% copper and 23% zinc). See also Karabin przeciwpancerny wz.35 Table of handgun and rifle cartridges Notes References Pistol and rifle cartridges Military cartridges World War II military equipment of Poland Military equipment of the interwar period Anti-materiel cartridges