That Gun is VERY interesting, It looks like (correct me if I am wrong) a Naval 4″ Deck Gun , from the WW1 Period, These Guns were also used in Coastal defenses in WW2…

Hi Merkle – We were discussing this on our way up to visit a HGW P-38 site this weekend – I’m no expert on heavy ordnance (well except 20mm :D) But 4″ naval gun of WW1 vintage was my conclusion also – think the coastal defense theory sounds pretty plausible too.