I believe this to be a IJN 25x163 Iype 96 cartridge from July of 1942. What is the arsenal mark on the left, which arsenal does it signify?
I see nothing on the left in your photo, if the right side a 0300 it looks like some one was playing with a punch.
Pete, I meant to the left of Showa (S). It is an arsenal mark but which?
OK, I found it, it is Dai Nippon arsenal.