The Kronshtadt-class battlecruisers, with the Soviet designation as Project 69 heavy cruisers, were ordered for the Soviet Navy in the late 1930s. Two ships were started but none were completed due to World War II. These ships had a complex and prolonged design process which was hampered by constantly changing requirements and the Great Purge in 1937. The main armament consisted of three electrically powered triple-gun turrets, each with three 54- caliber 305 mm B-50 guns. The turrets were based on the MK-2 turrets planned for the Project 25 large cruiser. The guns could be depressed to -3° and elevated to 45°. They had a fixed loading angle of 6° and their rate of fire varied with the time required to relay the gun. It ranged from 2.36 to 3.24 rounds per minute depending on the elevation.The turrets could elevate at a rate of 10 degrees per second and traverse at 5.1 degrees per second. 100 rounds per gun were carried. The gun fired 470-kilogram (1,040 lb) armor-piercing projectiles at a muzzle velocity of 900 m/s (3,000 ft/s); this provided a maximum range of 47,580 meters (52,030 yd). The secondary armament consisted of eight 57-caliber B-38 152 mm guns mounted in four twin-gun turrets concentrated at the forward end of the superstructure. The forward turrets were inboard and above the outer turrets which provided both turrets with good arcs of fire. Their elevation limits were -5° to +45° with a fixed loading angle of 8°. Their rate of fire also varied with the elevation from 7.5 to 4.8 rounds per minute. The turrets could elevate at a rate of 13 degrees per second and traverse at 6 de