I “inherited” a box of 38 Special reloads which were lathed to a much thinner rim and labelled “8mm Japanese revolver”. Firstly, which 8mm revolver? Secondly, how rare is surplus ammo that one had to lathe-form a different calibre?
Are you sure about the 8mm part? The only Japanese revolver round I am familiar with is a 9mm, for the M1893 (Type 26), which is a double-action only hinged frame Japanese revolver. The rim thickness is given as 0.028"-0.030". Cases for the 9mm Japanese revolver can be made by trimming .38 Special brass to a length of 0.862" and thinning the rims from the front side. The bullet diameter given is 0.360". That sounds like what you have. Standard references say that only about 60,000 revolvers were made between 1893-1924. I used to run across the revolver occasionally, but haven’t seen one in many years. Allegedly, it was carried mainly by Army NCOs.
After WWII, most captured Japanese small arms ammo was destroyed, and didn’t make it onto the surplus market. I think that was General MacArthur’s decision. Other than rounds brought back by GIs after WWII as souvenirs, original military Japanese-manufactured small arms ammunition is scarce indeed.
Thanks, they measure correctly for 9x22R Japanese.