Inside the tanks, tank destroyers, self-propelled guns, armored cars and halftracks were crews of flesh and blood. Soon after U.S. armored units entered combat, the lines between "tank," "tank destroyer" and "self-propelled mount" were quickly blurred. The Browning Machine Guns: Secondary Armament Of Primary ImportanceAlong with their main gun, American tanks were equipped with a potent mix of Browning machine guns. machine guns. machine guns.