A gun and its mounting
The Type 96 was a Japanese development of a Hotchkiss design. It appeared in single, twin and triple mountings. Some multiple mounts used power drives and a director; others were operated manually. A count of barrels does not tell us which control arrangements were available at each position. YT-Y22
The American investigators criticised the ability of the sights and power drives to follow fast targets at close range. Some Yamato-class triple mounts had shields intended principally to protect their crews from the blast of the main guns. Protection from blast did not make them invulnerable to an air attack.
Why 220 did not mean 220
The report gives a standard mechanical rate of 220 rounds per minute. But each magazine held fifteen rounds. Frequent changes reduced the rate that could actually be maintained to about 110. This is the investigators’ general assessment of the weapon, not a measured average for every gun aboard Yamato on 7 April. YT-Y22
Its shipboard inventory groups Yamato and Musashi together without establishing a dated final outfit for Yamato’s last sortie. We therefore do not use that table to certify an exact April 1945 gun total.
Still dangerous; increasingly difficult to use
Bennington’s VB-82 report describes intense anti-aircraft fire and records one missing aircraft. Its crews attacked several ships: the loss cannot simply be credited to Yamato’s 25 mm guns. The report nevertheless shows that the attackers faced active resistance. YT-Y20
From inside Yamato, Miyamoto described damage to anti-aircraft positions and the increasing difficulty of firing as the ship listed. The battle was changing the platform beneath the gun crews as well as destroying equipment. YT-Y01
The attack chapter follows those pressures together. Neither an impressive barrel total nor a low practical rate, taken alone, explains the loss of the ship.