 Their main armament consisted of eight 12-inch (305 mm) 50-caliber guns manufactured by Vickers. Each weighed 65.646 metric tons (64.609 long tons) and fired an 850-pound (385 kg) shell at a muzzle velocity of 3,000 ft / s (914 m / s). The guns had a maximum range of 23,500 yards (21,500 m) and a rate of fire of one round per minute. These guns were housed in four twin turrets, arranged with two on the centerline fore and aft, the others en echelon on the wings. The turrets were hydraulically operated, and could be loaded at any angle of elevation. The en echelon arrangement was chosen over superfiring turrets — such as those used in the American dreadnoughts — to save weight and cost. All four turrets could in theory fire on the broadside, and three could fire ahead or astern. However, blast effects from the wing turrets generally prohibited firing them across the deck or directly ahead and astern.
