Another tidbit about the Arisakas is the "Mum".
The Imperial Chrysanthemum was marked on every rifle. Normally on the top of the receiver ring. The rifles were technically the Emperor's property.
At the end of the war, the Japanese were required to surrender the rifles, and many, perhaps most, but by no means all, had the "mum" removed or defaced.
Stories differ about who did this, and where some say at the order of US officers in Japan, some say it was done when the guns were imported into the US, some say it was done by the Japanese before turning in the rifles, so they didn't dishonor the Emperor.
An Arisaka with an intact Mum was, for a long time, considered to be proof of a "battlefield pick up", an actual war trophy, and that is still often the case, but its no longer considered definite proof by itself alone as there have been verified examples of surrendered rifles with intact Mums, though not many,
A word about the 7,7 Jap, it is, literally the .303 British with a different, rimless case. Same diameter and weight bullets at the same speeds. Some old reloading manuals say to use the same data for both. More modern manuals show a difference in charge weights, usually around 2gr using IMR powders.
You can make 7.7mm brass from .30-06 cases. Shorten the 06 and run it through the 7.7 sizer and it works. Not quite as good as purpose made 7.7 cases but it will work acceptably well. (work up data for formed brass, of course)