The Japanese mounts you see house 125 mm cannons not 127 mm cannons, they just look the same.
Hi Oberst,
Understand that, but my comment was more on carrying two entirely incompatible types of artillery that are going to serve more-or-less the same purpose. For instance, once you've run out of 5"/38 (now that you have to have magazine space dedicated to 125mm, you're surely not going to be able to carry the same amount of 5"/38 ammo) do you just accept that you'll be unable to engage distant targets forward? Or, worse, do you reduce the quantity of 125mm carried and risk leaving yourself entirely unprotected aft? They stopped the practice of carrying many different calibres as far as possible prior to WWI, partly as a result of analysis of battles in 1905.
Regards,
Adam
Then I will concede and change the calibre of the Japanese mounts to 5 inch guns but they carry the same type of ammunition as they share the same barrel