 Their secondary armament consisted of sixteen BL 5 @.@ 5 @-@ inch Mk I guns , which were mounted on pivot mounts on the forecastle deck , protected by gun shields . They were provided with 200 rounds per gun . The guns on their <unk> mounts had a maximum elevation of 30 ° . They fired 82 @-@ pound ( 37 kg ) projectiles at a muzzle velocity of 2 @,@ 790 ft / s ( 850 m / s ) . Their maximum range was 17 @,@ 700 yd ( 16 @,@ 200 m ) at 30 ° elevation . Their rate of fire was twelve rounds per minute . 
