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 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 in silk bags, and provided a muzzle velocity of . 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 . Two turrets were mounted fore in a superfiring pair, while the other three were mounted aft of the main superstructure, all on the centerline. The placement of the rear gun turrets proved problematic. Capps placed the rear superfiring turret, Number 3, closest amidships. Since it represented the greatest weight borne by the ship's structure due to its tall barbette, this placement would allow it support by the greatest amount of underwater volume available. The other two rear turrets, Numbers 4 and 5, were placed level and back to back. This arrangement was detrimental in two ways. First, Number 3 could not fire astern with Number 4 trained forward, which left only the two 12" guns of Number 5 to do so. Second, because the engine room was situated between Numbers 3 and 4, steam lines ran from the boiler rooms amidships around the ammunition magazine for Number 3 turret to the engine room. These lines, it was later found, had the potential to heat the powder in the magazine and degrade its ballistics. This design flaw was also prevalent in several British dreadnoughts but was considered inescapable by naval designers on structural grounds. Another challenge with the main armament was that its weight, per turret, which had to be spread over much of the hull, led to increased stress on the structure. The closer the weight of the heavy guns to the ends, the greater the stress and risk for structural failure due to metal fatigue. High speed required fine ends, which were not especially buoyant, and the amount of space needed amidships for machinery precluded moving the main turrets further inboard. Not having to worry about a displacement limit allowed Capps the option of deepening the hull, which helped to