 The Delawares mounted fourteen 5 @-@ inch / 50 caliber Mark 6 guns , two forward on the main deck , 10 inch casemates on the side and two aft on the main deck abeam No. 5 turret . They had a rate of fire of 6 to 8 rounds per minute . They fired three types of rounds : a " light " AP shell that weighed 50 lb ( 23 kg ) and a " heavy " AP round that weighed 60 lb ( 27 kg ) . The third type was the Common Mark 15 shell , which also weighed 50 lb . The 50 lb shells were fired at a muzzle velocity of 3 @,@ 000 ft / s ( 914 m / s ) , while the larger 60 lb shells traveled at a slightly slower 2 @,@ 700 ft / s ( 823 m / s ) . The guns were emplaced on both Mark 9 and Mark 12 pedestal mounts ; the Mark 9 version limited elevation to 15 degrees , while the Mark 12 allowed for up to 25 degrees . The 5 @-@ inch / 50 was able to penetrate most effectively at 5 @,@ 000 yd ( 4 @,@ 572 m ) , which was the deciding factor in the decision to equip the Delaware class with them . The 5 @-@ inch guns were supplied with a total of 240 rounds per barrel . 
