The 13-inch gun was 35 calibers long and used black powder, giving a range of about at 15 degrees of elevation. At , a shell was expected to penetrate of side armor. The four guns were mounted in two centerline turrets, located fore and aft. The turrets were originally designed to feature sloping side armor, but space requirements made this impossible without using significantly larger gun turrets or redesigning the gun mounts (which was later done for the s). The ships' low freeboard greatly hindered the use of the main battery in rough weather conditions, because the deck would become awash. Also, because the ship lacked a counterweight to offset the weight of the gun barrels, the ship would list in the direction the guns were aimed. This reduced the maximum arc of elevation (and thus range) to about five degrees, brought the main armor belt under water on that side, and exposed the unarmored bottom on the other. It was considered in 1901 to replace the turrets with new balanced models used in later ships, but that was decided to be too costly as the ships were already obsolete. Instead, counterweights were added, which partially solved the problem. The hydraulic rammers and turning mechanisms of the 8-inch turrets were also replaced by faster and more efficient electric equivalents, new sights were fitted on "Indiana" and "Massachusetts", and new turret hoists were installed to improve the reloading speed, but the gun mountings never performed in an entirely satisfactory manner.