This was explained on another thread, but I guess it bears repeating here. Information about this, and lots more on post-WWII Japanese ammunition, is primarily by courtesy of Mr. Hiromasa Ikeda, one of the former heads of the Japanese National Police Crime Lab and later a lecturer at the Kyushu Regional Police Bureau Police Academy, who I had the honor of meeting on several occasions during visits made by Ikeda San to AFTE Meetings in the US. He would come thru San Francisco, and come to the gun shop I worked at. On the last visit I had with him at the store, he left me all of his notes on Japanese post-WWII small arms ammunition, from a presentation he had made at the AFTE meeting.
The “W” before the digits representing the date of case manufacture stands simply for “Weapon.” It is only found on cartridges made for the JDF. The reason for the use of this initial was never clear to me. Mr. Ikeda did not speak much English and I do not speak Japanese. It was assumed that the “W” referred to the date being expresses according to the Western Calender. That made sense, and was well accepted, even though it was proved to be incorrect.
Post-war Japanese cartridges, especially pistol rounds, are among the hardest specimens to find outside of Japan among those of any other countries. I have only one Japanese 9 x 19 mm Luger cartridge, headstamp J - A O A 6 2. I know of also, for the Ikeda notes, of the headstamp J - A O W 8 7., identical in font and spacing to the 95-date cases shown at the beginning of this thread. They are a product of the company initiated as Asahi-Okuma Arms C., Ltd. founded in August 1953. Production of military ammunition there began at least as early 1955, with sporting ammunition, in the form of paper shotgun shells began in May of 1958.
In January 1961, Asahi-Okum purchased the entire manufacturing plant of Toyo Seiki Co., Ltd. Since that time, it has been the sole manufacturer of metallic small arms ammunition under .50 caliber in Japan, although other companies have made shoshells.
Also existing is the National Police Agency Ammunition Plant, but this has been in the past a loading factory only, using components primarily supplied by Asahi-Okuma, except for waged lead bullets, which evidently are manufactured by the Police Plant.
thank you, Brian, for starting this thread and for the pictures of the 9 mm box label, the first I recall seeing, unless there was one on the recent thread also showing relatively current Japanese box labels, as well as that 9 mm “95” dated headstamp.
Reference and for further reading: PostWWII Small Arms Ammunition Production, in Japan, Woodin Laboratory compiled by John L. Moss, California Cartridge Collectors’ Association Bulletin Volume 17, Numbers 4 and 5, August and October 1997.