The 15.2cm guns were originally designed by Vickers as secondary weapons for the battlecruiser Kongo, which was built in Britain by Vickers-Armstrong (Barrow). The Japanese version was designed by Engineer Hata Chiyokichi and adopted in 1908. In the Japanese Navy, Vickers-built guns were designated as Mark II while those built in Japan were designated as Mark III. The design itself was outstanding at its time, but 15.2 cm shell proved too heavy for Japanese sailors and had inferior firing rate (circa 6rpm), thus the lighter variant of 14cm caliber was later designed in-house. | The 15.2cm guns were originally designed by Vickers as secondary weapons for the battlecruiser Kongo, which was built in Britain by Vickers-Armstrong (Barrow). The Japanese version was designed by Engineer Hata Chiyokichi and adopted in 1908. In the Japanese Navy, Vickers-built guns were designated as Mark II while those built in Japan were designated as Mark III. The design itself was outstanding at its time, but 15.2 cm shell proved too heavy for Japanese sailors and had inferior firing rate (circa 6rpm), thus the lighter variant of 14cm caliber was later designed in-house. |