from severe design shortcomings that rendered it a largely ineffective weapon. According to historian Mark Stille, the twin and triple mounts "lacked sufficient speed in train or elevation; the gun sights were unable to handle fast targets; the gun exhibited excessive vibration; the magazine was too small, and, finally, the gun produced excessive muzzle blast". These 25 mm guns had an effective range of , and an effective ceiling of at an elevation of 85 degrees. The maximum effective rate of fire was only between 110 and 120 rounds per minute because of the frequent need to change the fifteen-round magazines. Additional Type 96 guns were installed during the war; on 10 July 1944, the ship was reported to have 98 guns on board. An additional 30 guns were added during a refit in Yokosuka in November. Two more twin 12.7 cm (5 inch) gun mounts were added at the same time abreast the funnel and her 14 cm guns were removed as she was by then a floating anti-aircraft battery. Armor The ship's waterline armor belt was thick and tapered to a thickness of at its bottom edge; above it was a strake of armor. The main deck armor was while the lower deck was thick. The turrets were protected with an armor thickness of 305 mm on the face, on the sides, and on the roof. The barbettes of the turrets were protected by armor 305 mm thick, while the casemates of the 1 guns were protected by armor plates. The sides of the conning tower were thick. The new 41 cm turrets installed during Nagatos reconstruction were more heavily armored than the original ones. Face armor was increased to , the sides to , and the roof to . The armor over the machinery and magazines was increased by 38 mm on the upper deck and on the upper armored deck. These additions increased the weight of the ship's armor to , 32.6 percent of her displacement. In early 1941, as a preparation for war, Nagatos barbette armor was reinforced with armor plates above the main deck and plates below it. Fire control and sensors When completed in 1920, the ship was fitted with a rangefinder in the forward superstructure; and anti-aircraft rangefinders were added in May 1921 and 1923, respectively. The rangefinders in the second and third turrets were replaced by 10-meter units in 1932–1933. Nagato