46cm/45 Type 94 Main Battery Guns were the largest, and possibly still are, guns used for Navy usage. It is 18.1 Inches in diameter, meaning it was about 3-2 inches larger than other Navies guns.The Ships, Musashi and Yamato both used the same guns.
The guns mounted on the Musashi and the Yamato were used triple-barreled, meaning there was three 46cm guns on each turret, making 9 in total, three guns on three turrets. During World War II, the 46cm guns were purposefully called 40cm/45 Type 94 Naval guns, to trick other nations that it was smaller than intended. Some 27 guns were built, while two thirds of them were sunk with Musashi and Yamato.
Its effective firing range was 16 miles (25km) and its maximum range was 26 miles (42km) Each of the shells shot by the 46cm guns weighed in over a ton and a half. Each turret and gun weighed in about 2,510 tons, the same tonnage a destroyer of the same era would weigh. It's rate of fire (ROF) was about 1 to 2 rounds per minute. It's muzzle velocity is around 780 m/s (2600 ft/s)
Sources: Myself, Wikipedia
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