 The Admiral @-@ class ships were designed with four QF four @-@ inch Mark V anti @-@ aircraft guns . They had a maximum depression of -5 ° and a maximum elevation of 80 ° . They fired a 31 @-@ pound ( 14 kg ) high explosive shell at a muzzle velocity of 2 @,@ 387 ft / s ( 728 m / s ) at a rate of ten to fifteen rounds per minute . The guns had a maximum ceiling of 31 @,@ 000 ft ( 9 @,@ 400 m ) , but an effective range of much less . 
