Asahi 's main battery consisted of the same four Elswick Ordnance Company 40 @-@ calibre twelve @-@ inch guns used in all of Japan 's preceding battleships . They were mounted in twin @-@ gun turrets fore and aft of the superstructure . The hydraulically powered mountings allowed the guns to be loaded at all angles of traverse , at a fixed elevation of + 13 @.@ 5 ° . Each mount could traverse a total of 240 degrees . They fired 850 @-@ pound ( 386 kg ) projectiles at a muzzle velocity of 2 @,@ 400 ft / s ( 730 m / s ) .