Comments by "Sar Jim" (@sarjim4381) on "IJN Taiho - Always Train Your Crew" video.

Japan had the AA guns she needed when she captured British examples of 40mm Bofors and 20mm Oerlikon guns when Singapore was captured. Japan was never able to master the close tolerances needed for both weapons, although she continued to produce evaluation copies to just about the end of the war. The IJN knew the 25mm gun was not the best weapon for fighting off allied aircraft, but she had been making various models of Hotchkiss guns since the early '30s and had mastered the tolerances required for them. Later types like the Bofors required better materials and machine tools, things in short supply by the time the first preproduction samples of the Japanese Bofors were ready in 1943. Japan was producing about 1,500-2,000 25mm barrels a month in 1943, and even the most optimistic estimates for the 40mm Bofors was 5-10 barrels a month. It was a matter of fighting with something rather than nothing.
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@Drachinifel Well, Thursday is Thanksgiving Day here in the US, so the video gives us something else to be thankful for. :-)
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@Raptor747 That really wasn't the issue. The Japanese were able to produce good reverse engineered copies of the 40mm. They just couldn't do it without a lot of hand work, didn't have the kinds of steels needed, and weren't able to produce them in numbers that would have made any difference. Remember that US, with a complete set of working drawings, several examples of the 40mm gun, and the vast industrial ability of the country in early 1940, still took almost two years to produce the first twin mount in January, 1942, and over two years to produce the first quad mount in April, 1942. The Japanese just didn't have the industrial capacity to produce the 40mm gun in any numbers regardless of the ROF or muzzle velocity.
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@paulhinds4840 You're thinking of the US 28mm (1.1") guns. The Japanese has a 25mm gun. They did gain a rudimentary form of fire control toward the end of the war. In addition to the training being too slow, the laying was equally slow since it was all done by hand. The 25mm round was too small for any kind of explosive flak type charge, and it had the same issues as the US 28mm guin - the charge was just too small to reliably bring down an aircraft, even after multiple hits. The other major problem was the poor effective AA ceiling. It was less than 10,000 feet compared to the US 1.1" ceiling of 19,000 feet. One of the reasons why our aircraft attacks against Japanese ships were so effective was dive and torpedo bombers could orbit around five miles out at 15,000 feet until they saw an opportune time to attack and be out of range of Japanese light AA.
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@comandercarnis They did the reverse engineering in 1942. The problem wasn't that it was too late, it was they didn't have the machine tools to manufacture parts to the tolerances demanded by the gun. They made something like 25 guns a year in 1943 and 1944 as test guns, but they mostly stopped trying by 1945 because they couldn't get them to run reliably. If they had, Japanese vessels would have had Bofors guns by late 1943.
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