The Gryazev-Shipunov GSh-23 (Russian: ГШ-23) is a twin-barreled 23 mm autocannon developed in the Soviet Union, primarily for military aircraft use. It entered service in 1965, replacing the earlier Nudelman-Rikhter NR-23 cannon. The GSh-23 works on the Gast Gun principle developed by German engineer Karl Gast of the Vorwerk company in 1916. It is a twin-barreled weapon in which the firing action of one barrel operates the mechanism of the other. It provides a much faster rate of fire for lower mechanical wear than a single-barrel weapon.