Dear Friend, thank you so much! Finally some good pictures of the Chinese HIH naval guns!
Number 2 and 4 pics show the HIH Siderius 15cm naval gun, also used (3 pieces) by the Dutch Navy on the Johan Maurits van Nassau gunboat. One gun remains at the Den Helder Naval base. This weapon is closely related (through some breech features) to the Rheinmetall 15cm naval guns of the 1920s and 30s.
Some pics of the gun can be found here:http://www.network54.com/Forum/330333/m ... More+shots
Now the 7,5cm naval AA gun. It is not the HIH 7,5cm L55 as used by the Dutch Navy. That was a more modern gun, used on Dutch destroyers (not German!) of the Banckert and Van Nes class as well as some minelayers:http://www.network54.com/Forum/330333/m ... +Navy+guns
I think there was a now defunct or moved ROC website dealing with naval history that had these guns listed as L40, seehttp://www.network54.com/Forum/330333/m ... Naval+guns
With this L40 calibre HIH merely continued a line of Krupp 75mm L40 naval gun. Actually, I am not sure if this is an original weapon or an upgraded or bored out existing one, like the Hotchkiss. Meanwhile I have acquired some factory pictures of the HIH 75 mm L40, not for publication. I will pm you one. I am convinced the Chinese naval AA is this 75mm L40. I am speculating that this was a completely rebuilt Vickers (Elswick) 76mm/3 inch/12 pounder naval gun, retaning at least the outer barrel. This was a far more complicated operation that converting the 57mm naval guns, that could be done in any naval arsenal. Any thoughts welcome!