"The A-10A's armament is extremely impressive, particularly if you are on the receiving end. The A-10 is essentially designed around its gun, the largest and most powerful cannon carried by any combat aircraft todya, the GE GAU8/A Avenger, which a 30mm Gatling un. Many modern jet fighters and attack plances carry 30mm cannons, none of them approach the GAU-8/A's power. It fires a .78-pound, 30mm armor-piercing projectile at a muzzle velocity of 3,500 feet per second. This is a very heavy projectile for an automatic cannon, and that's a very high velocity. These are not ordinary armor-piercing projectiles. The armor-piercing penetrators are fabricated from depleted uranium, an extremely dense material with outstanding armor-piercing capability. What happens after the armor has been penetrated has to be seen to be believed! Heated by the tremendous energy of the impact, the depleted uranium oxidizes rapidly and violently, spraying the indside of the armored vehicle with flaming metal fragments that ignite fuel and detonate ammunition. The A-10A carries 1,174 rounds of 30mm ammunition, and the pilot can select one of two rate of fire, either 2,100 or 4,200 rounds per minute."
From p13 Target Terrorism by Pat Rogers, pub. Pantheon Intl, Ltd. NY.