 The guns could initially be depressed to − 3 ° and elevated to 13 @.@ 5 ° , although the turrets were modified to allow 16 ° of elevation during World War I. They fired 850 @-@ pound ( 390 kg ) projectiles at a muzzle velocity of 2 @,@ 725 ft / s ( 831 m / s ) ; at 13 @.@ 5 ° , this provided a maximum range of 16 @,@ 450 m ( 17 @,@ 990 yd ) with armour @-@ piercing ( AP ) 2 crh shells . At 16 ° elevation , the range was extended to 20 @,@ 435 yd ( 18 @,@ 686 m ) using the more aerodynamic , but slightly heavier 4 crh AP shells . The rate of fire of these guns was 1 – 2 rounds per minute . The ships carried a total of 880 rounds during wartime for 110 shells per gun . 
