 The Delaware @-@ class ships were armed with ten 12 @-@ inch / 45 caliber Mark 5 guns in five twin gun turrets ; this was an addition of two guns compared to the preceding South Carolinas . The gun housings were the Mark 7 type , and they allowed for depression to − 5 degrees and elevation to 15 degrees . The guns had a rate of fire of 2 to 3 rounds per minute . They fired 870 lb ( 395 kg ) shells , of either armor @-@ piercing ( AP ) or Common types , though the Common type was obsolete by 1915 and put out of production . The propellant charge was 310 lb ( 141 kg ) in silk bags , and provided a muzzle velocity of 2 @,@ 700 ft / s ( 823 m / s ) . The guns were expected to fire 175 rounds before the barrels would require replacement . The two ships carried 100 shells per gun , or 1 @,@ 000 rounds in total . At 15 degrees elevation , the guns could hit targets out to approximately 20 @,@ 000 yd ( 18 @,@ 288 m ) . 
