The Gryazev-Shipunov GSh-30-2 or GSh-2-30 is a Soviet dual-barrel autocannon developed for use on certain ground attack military aircraft and helicopters.
The 30 mm caliber is a range of autocannon ammunition. It includes the NATO standardized Swiss 30×173mm, the Soviet 30×155mmB, 30×165mm and 30×210mmB, the Czechoslovak 30×210mm, the Yugoslav 30×192mm,