I expect there's a fair number of Arisaka owners who've never seen original WW2 Japanese military cartridges in 7.7mm or 6.5mm. I have a handful of 7.7x58 cartridges but only one 6.5.
The Japanese 7.7 cartridges are color coded around the case neck. The left one is purple and the right one is red. It would be nice if I could remember what the colors indicated!! One of them is incendiary (red?) and as I recall the incendiary are considered unstable and dangerous if DROPPED. I tend to handle them carefully as I have several of the incendiary. I think the purple may be armor piercing but correct me if I'm wrong.
I also have an 8mm Nambu cartridge. None of the WW2 Japanese military cartridges have any headstamp information.