The GSh-6-30, designed in the early 1970s and entering service in1975, has asix barrel design that is similar to theGryazev-Shipunov GSh-6-23. It was based on the naval AO-18 used in theAK-630 system. Unlike most modern rotary cannons, it is gas-operated rather than hydraulically driven, allowing it to "spin up" to maximum rate of fire more quickly, allowing more rounds to be placed on target in a short-duration burst. This makes the weapon advantageous in dogfights, where pilots often have a very small window for engaging the enemy. Ignition is electrical, as with the smaller GSh-6-23.
On theMiG-27 "Flogger" the GSh-6-30 had to be mounted obliquely to absorbrecoil. The gun was noted for its high (often uncomfortable) vibration and extreme noise. The airframe vibration led to fatigue cracks in fuel tanks, numerous radio and avionics failures, the necessity of using runways with floodlights for night flights (as the landing lights would often be destroyed), tearing or jamming of the forward landing gear doors (leading to at least three crash landings), cracking of thereflector gunsight, an accidental jettisoning of the cockpit canopy and at least one case of the instrument panel falling off in flight. The weapons also dealt extensive collateral damage, as the sheer numbers of fragments from detonating shells was sufficient to damage aircraft flying within a 200-meter radius from the impact center, including the aircraft firing.[4]
The principal application for the GSh-6-30 is theMiG-27, which carries the weapon in a gondola under thefuselage, primarily for strafing and ground attack. It was fitted to someSu-25TM aircraft, but subsequently replaced with theGSh-30-2 twin-barreledautocannon of the original Su-25. It is also used as the gun component of theCADS-N-1 Kashtanclose-in weapon system.
