 The main armament of the Ibuki class was intended to be ten 50 @-@ caliber 20 cm 3rd Year Type No. 2 guns mounted in twin turrets , three forward and two aft of the superstructure , numbered one through five from the bow to the stern . The first two forward turrets were on the same level , but the third turret could superfire over the first two . The guns could depress to − 5 ° and had a maximum elevation of 55 ° . They fired 125 @.@ 85 @-@ kilogram ( 277 @.@ 5 lb ) projectiles at a muzzle velocity of 840 m / s ( 2 @,@ 800 ft / s ) . They had a maximum range of 29 @,@ 400 yd ( 26 @,@ 900 m ) at an elevation of 45 ° and the ship carried 128 rounds per gun . The secondary armament was to consist of eight 40 @-@ caliber 12 @.@ 7 cm Type 89 anti @-@ aircraft ( AA ) guns in twin mounts . They fired 23 @.@ 45 @-@ kilogram ( 51 @.@ 7 lb ) projectiles at a rate between 8 and 14 rounds per minute at a muzzle velocity of 700 – 725 m / s ( 2 @,@ 300 – 2 @,@ 380 ft / s ) ; at 45 ° , this provided a maximum range of 14 @,@ 800 meters ( 16 @,@ 200 yd ) , and a maximum ceiling of 9 @,@ 400 meters ( 30 @,@ 800 ft ) . The ships were also intended to be equipped with four twin 25 mm Type 96 light AA guns abreast the funnel . They fired .25 @-@ kilogram ( 0 @.@ 55 lb ) projectiles at a muzzle velocity of 900 m / s ( 3 @,@ 000 ft / s ) ; at 50 ° , this provided a maximum range of 7 @,@ 500 meters ( 8 @,@ 202 yd ) , and an effective ceiling of 5 @,@ 500 meters ( 18 @,@ 000 ft ) . The maximum effective rate of fire was only between 110 and 120 rounds per minute due to the frequent need to change the fifteen @-@ round magazines . Two twin 13 @.@ 2 mm Type 93 machine gun mounts were supposed to be mounted on the bridge with 2 @,@ 000 rounds per gun . 
