Battle Damaged(?) Data Plate

[Ryoyo]

Got this in today thanks to having too much time to browse eBay. A heavy brass or bronze data plate that appears to have a bullet or shrapnel strike to the top left. When I saw the photos at first I thought it might have been damaged by whoever removed it, but on closer examination it does look like a bullet strike.
I can read some Japanese, but due to the damage I haven't yet figured out what it came from. The top seems to be a Showa 3 date followed by 改 and then the rest obliterated. The bottom looks like "株式会社日本製鋼所"Japan Steel Works
Anyone have a similar plate and know what it's from? Or maybe a more fluent Japanese reader might be able to make a better guess at the missing/damaged kanji.

[Nick Komiya]

There is no indication of what it came from. The top line says it was a model modified in 1928, and you got the manufacturer's name at the bottom right.

[Ryoyo]

I'm going to guess it is probably from some piece of artillery since it seems to be a heavy duty plate and Japan Steel Works made that sort of thing. Hopefully someday I'll find a photo of one that can solve the mystery.

[Long Shot]

Nick states: There is no indication of what it came from.

I'm going to guess it is probably from some piece of artillery since it seems to be a heavy duty plate and Japan Steel Works made that sort of thing.

That's a far stretch of "a guess" in the face of facts

[Nick Komiya]

Here's how such plates looked from 1942 in code. The company name of Nihon Steel became a simple イ

[Jareth]

It appears the damage might of occurred when it was pried off rather than battle damage