The cannon is a 27mm single-barrel, high performance, breech-cylinder gun operated by a fully automatic, electrically fired gas-operated system at a selective rate of 1,000 or 1,700rpm.
Targeting of the cannon is done through the aircraft’s head-up display. The cannon has a very high muzzle velocity and its high rate of fire, coupled with its ability to fire several different types of high-explosive and armour-piercing rounds, makes it equally suitable for both interceptor-type aircraft and ground-attack aircraft alike.
The belted-link ammunition box is positioned to the side of the gun-feed mechanism and a floating buffer system imposes a very small recoil and vibration load on the airframe of the aircraft. Spent cartridge cases and empty links are ducted from the rear of the gun into a collection bay immediately behind the gun. Automatic ram air purges the gun compartment and spent cases bay during and after firing.
The weapon has a very good hit-accuracy and one of its main strengths is the cannon’s ability to achieve a full 1700-rounds-per-minute rate of fire almost from the first round. This is an important asset, particularly if the cannon is being used against a fast-moving target. Targeting of the cannon is done through the aircraft’s head-up-display (HUD). When the cannon is selected in the cockpit, a firing predictor is projected onto the HUD; this depicts a moving line (continuously compacted impact line), or snake, that predicts where the next few rounds of cannon fire will go.