 An additional 4 @-@ inch gun was fitted in the surviving ships during 1917 as an anti @-@ aircraft ( AA ) gun . It was mounted on a Mark II high @-@ angle mounting with a maximum elevation of 60 ° . It had a reduced propellant charge with a muzzle velocity of only 2 @,@ 864 ft / s ( 873 m / s ) . Earlier anti @-@ aircraft guns included a single QF 3 @-@ inch ( 76 @.@ 2 mm ) 20 cwt AA gun on a high @-@ angle Mark II mount that was added during refits in 1914 – 15 . This had a maximum depression of 10 ° and a maximum elevation of 90 ° . It fired a 12 @.@ 5 @-@ pound ( 5 @.@ 7 kg ) shell at a muzzle velocity of 2 @,@ 500 ft / s ( 760 m / s ) at a rate of fire of 12 – 14 rounds per minute . They had a maximum effective ceiling of 23 @,@ 500 ft ( 7 @,@ 200 m ) . It was provided with 500 rounds . New Zealand carried a single QF 6 pounder Hotchkiss AA gun on a HA MkIc mounting from October 1914 to the end of 1915 . This had a maximum depression of 8 ° and a maximum elevation of 60 ° . It fired a 6 @-@ pound ( 2 @.@ 7 kg ) shell at a muzzle velocity of 1 @,@ 765 ft / s ( 538 m / s ) at a rate of fire of 20 rounds per minute . It had a maximum ceiling of 10 @,@ 000 ft ( 3 @,@ 050 m ) , but an effective range of only 1 @,@ 200 yards ( 1 @,@ 097 m ) . 
