 Later designs called for eight 16 " / 50 caliber Mark 2 gun , also slated to be used on the South Dakota @-@ class battleship of 1920 . Like the 14 " / 50 caliber gun , the 16 " gun was designed in 1916 . Basically an extended version of the 16 " / 45 caliber Mark 1 gun used on the Colorado class , it fired the same 2 @,@ 100 @-@ pound ( 950 kg ) shell as the Mark 1 at a muzzle <unk> of 2 @,@ 800 fps ( 853 mps ) and rate of two rounds per minute to a range of 44 @,@ 500 yards ( 40 @,@ 700 m ) at an elevation of 45 degrees . 
