This is the only mark on the head of what I have identified as a 7.7 Japanese (Arisaka) cartridge but due to wear I can’t be certain what it really is. Below are sketches of what it appears to be to me. The 1st appears most likely correct, unless the openings are due to damage/wear. Attempts to scan or photograph results were just to poor to even post. This thing is very small.
The image, as you see it, would be at 3:00 o-clock between the primer crimp, which is very pronounced, and the outer rim. I needed a 10X magnifier to really see it, in good light.
I’ve searched the site and found nothing, also several other sources. Does anyone know anything about this? The age and condition of the cartridge leads me to believe it is post WWII but the primer crimp looks very similar to Japanese wartime crimps.