Hi Falcon,
You ask a simple question, and are about to get a very complicated 'answer' (or elaboration at least), that may leave you more puzzled than you were before.
These casings are one of the (to me, at least) great enigmas in "Japanese" ammunition. Essentially they are of a Russian calibre, being the 76.2x385R, being just about the most ubiquitous Russian used artillery calibre. I am not certain if these casings were manufactured in Russia for Japan, or vice versa. Initially I thought they were Russian manufactured for Japan, but nowadays I'm not certain. I'm in favour of them being Japanese manufacture for Russia, but some motivations why I can't quite put my finger with certainty on it:
1-The only Japanese markings are the ones appearing at the 12 o'clock position. They show the Osaka arsenal mark, along with either an 'F' or (as is the case on this specimen) an 'M' and a variety of other letters, at time 'DYAO', on others only a 'Y'. The Osaka arsenal was an Army arsenal, and AFAIK the IJA did not use anything in 76.2mm calibre, but rather they used the 75mm calibre extensively. The calibre seems to support the idea of them being manufactured for Russia, but the markings show no Japanese style manufacturing date, unless these were stamped in Russian style dates. This brings me to the next point:
2-The case is marked '16' at the 3 o'clock position. All specimens I have seen have either a '15' or a '16'. These were explained to me as Russian style date markings, being 1915 and 1916, IOW: well in WW1 before the Russian revolution, so one would think the Russians could use this ammo pretty well themselves, rather than selling it to Japan. I nowadays think these markings were not made BY the Russians, but rather FOR the Russians, by the Osaka arsenal.
3-At least one of the specimens I have has a Russian primer, BUT it is marked 1944. Of course this may have been screwed in later by someone, or... ...it may still have been used as late as 1944!
4-Ammo that was imported by the Japanese was, AFAIK, not arsenal stamped. At least the IJN imported items were never arsenal stamped. They did feature Japanese acceptance stamps, however. These particular casings DO feature an arsenal stamp (i.e. Osaka) but feature none of the acceptance stamps of the IJA that I'm aware of. This to me is one of the strongest motivations for thinking these to have been manufactured as a Russian contract fulfilled by the Japanese.
4-Now for a really, really confusing point: some of these casings feature the notorious 'F' markings (another great enigma on Japanese IJA ammo), but... ...on typical IJA ammo this has so far ONLY be seen by me on Showa era ammunition, i.e. AFTER 1925. This is seemingly at variance with the 'F' marking being present on this casing, as well as a date of 1916! The 'M' marking is, AFAIK, never seen on any other IJA ammo. By elimination, Lothar and I came to the assumption that the 'F' is only present on Showa era IJA brass casings (not on all of them!), and not on steel casings, nor on IJN casings, nor on pre-Showa casings. The (to me!) most likely correct interpretation seems to be that it is some brass strength/quality/composition marker. It's odd that no Kanji or Katakana character was used. Several Taisho era (i.e. 1911 - 1925) casings do feature a single Kanji at the 12 o'clock position. I have yet to get these interpreted, but I've got a strong suspicion it is the predecessor of the later 'F'. In light of these Russian casings, I have developed a new theory: I think it is very well possible that the Russians only wanted Western (or Cyrillic) markings on their headstamps, and that the 'F' indicated the casing to be strong enough to support a 'Full' charge, and the 'M' indicating a 'Moderate' charge, or something like that. Do note that I stress that this is so far ONLY a theory, but it IS something I'm trying to delve deeper into.
5-One possibility that supports the presence of the 'F' on the one hand, and the 1916 on the other hand, is that these casings were actually Russian surplus casings, sold to Japan after the Russian revolution, and that the Osaka arsenal refurbished them. But.... if that is really the case, the Japanese would have needed matching 76.2mm field guns too. I have no records of Japanese usage of this calibre, but it is a possibility.
6-One final observation is that these casings are seen relatively often in Europe. I personally own 4 of them (2 with 'F' markings, 2 with 'M' markings) and know of several other collectors who own them. This contrasts the sparse availability of even the most common of true Japanese calibre 75mm casings seen over here. This leads me to think that these particular casings came out of Russia, rather than out of Japan. Again, mere conjecture, but it is somewhat supported by this "circumstancial evidence".
Darn it's time I write this stuff on a page under my "Unsolved Mysteries" menu on my site:
http://www.japaneseammunition.com
If someone has further specimens I'd welcome pictures of them, and/or if anyone knows anything of contracts that the Japanese fulfilled for the Russians or vice versa, I'd be extremely interested in finding out more details about them!
To be continued... (I hope!)
Cheers,
Olafo
