trench art made from shells, etc. Can anyone identify the shells used in this gong

[Lost n Found]

Hi guys, just got a trench art dinner gong? Amazing piece. The base plate is japanese, about 40 cm across, its brass with numbers round the outside and japanese characters all over it, It is then mounted on a timber plinth, would love to know what that is off? The supports and the crossbar are brass. The gong is a large shell 17cm across with 2 smaller shells to hang it from the crossbar. The 2 smaller shells have U 4 3 on the bottom. The large shell has Japanese characters on the base and a cross where its been fired. It is also engraved with a natives head on 1 side of it as decoration.
I know it was brought back from New Guinea but thats about all i could find out. Any help as to dating, valueing the item and identifying what shells its made from, and specially the big brass base plate will be much appreciated.

[Wagriff]

Can't help you on translating the plaque, but I sure do like this item!

[Wolfe1165]

My Japanese is very limited, but the first line of the plaque(pic is upside-down) says "October of the 30th Showa year - 1955" I can't read the second line, is it possible to get a closer shot? The base plate itself is interesting. I don't know much about large artillery, but it has the kanji for left and right "左, 右" so it must have something to do with trajectory. Sorry I'm not much help, I've only been learning Japanese for a little while.

[Lost n Found]

Thank you all for your help. Here is a pic of the plaque close up and right way round. I'm wondering if the disc is a rangefinder or something? off a big gun, and the big shell came out of it??

[TonyE]

I cannot tell you anything about the plinth, although I agree it looks like a range table or similar, but the two smaller cartridges are American .50 Browning HMG rounds made at the Utah Ordnance plant, Salt lake City, in 1943.

Regards
TonyE