シンガポールの15in砲だが照準器は旧式らしい
https://singafood.exblog.jp/12084661/


>　The 15-Inch Gun had a length of 52'5" (16 metres), and fired a shell weighing 1938 lb (879 kg).
>The shell left the barrel at 2,575 feet per second (785 metres per second. The guns at Singapore had an elevation of 45°, and a range of 36,900 yards (33,741 metres).

最大射程は分かったが発射速度が不明だな