Page 16 of the current Shotgun News has an article by Paul Scarlata on the elusive Japanese Type I. More Type I information in one place than ever before, including my humble attempt.
(Also, I'd totally forgotten that Hornady was doing 6.5x50mm Arisaka ammo for Graf & Sons. 20 rounds of loaded ammo cheaper than you can buy 20 rounds of unprimed brass from Norma. W00t!)