Hi,
Well, as the Dutch NVBMB members will know, I've put some effort into doing further research about these rounds and their manufacturer. Down below follows an overview (summarised) of my findings. The ID of the manufacturer was made by a different NVBMB member who translated a part of the Japanese writing on the box, and came up with the manufacturer's name ("Nippon Koki") and website.
Here goes:
I came across an ammo box of 20x102 TP rounds in Japan and it's not the first of its kind that I have seen over there. Pictures of it are added to this reaction. The box clearly has Japanese writing on it, and I myself could easily read the date of manufacture to be "Showa 59-12", which is December 1984. I could also easily read the Kanji for "Nippon" (= "Japan") on two locations on the box. Furthermore, on the inside we find a.o. Katakana writing. There's no way that this box was made (or at the very least, stamped) in any other location than Japan. I also noticed a second date, being Showa 61.2 (February 1986). I figured that information to be the filling date, but it is not, the aforementioned other NVBMB member had it translated to read "Kashi tanpo kigen" which translates to something like: "minimum guaranteed period without failure". He also mentioned that the 'Nippon' part that I had already seen is actually part of the company name: "Nippon Koki ltd". He went on to come up with a link to the manufacturer's website:
http://www.nippon-koki.co.jp and look what we find on this page:
http://www.nippon-koki.co.jp/product/gun.html
Blimey! There they are, along with the TP and AP and HE kinds, and some .50 rounds that I also come across occasionally in Japan!
So, DEFINITELY of Japanese manufacture.
But wait. There's more.
Before the translation and manufacturer ID were provided, I already reasoned that the 'NS' numbers on the blanks were analogous to what can be seen on the box (which is why I refer to that particular box in the first place). Note the number on the box: "NS-4028-59". The 'NS' is then (as we know now) 'Nippon Koki', the '4028' is almost certainly a lot number and the '59' is almost beyond a doubt the year of manufacture (Showa 59; i.e. 1984). Now look at the numbering on the blanks. The 'NS' numbers use an analogous numbering format, but tend to end in lower numbers, mostly 14, 15, 16. No problem. These ought to be years in the Heisei period then (i.e. the current one, of emperor Akihito, following the Showa era that ended with the death of emperor Hirohito on January 7th, 1989). 14 = 2002, 15 = 2003, 16 = 2004.
Lastly, a further round was shown that is obviously older (darker and higher positioned text). It has a '63' in that position. Still no problem. Surely it must have been made in Showa year 63, being 1988!
Now, I would bet that ANY specimen found will have a number at that position of maximally 64 (which is not very likely to be encountered, unless production took place in the first days of January 1989 and is found). With Heisei year 26 being 2014, I would also bet that there is a good stretch after '26' (but below '63') of numbers that are also not encountered.
I'll explain.
Heisei 26 = 2014.
Showa 26 = 1951.
Surely Showa 27 (i.e. 1952) would be VERY early for this kind of ammo. Heisei 27 is in the future.
AFAIK, the M39 was the first cannon that used the 20x102 calibre. It doesn't help the above quest that it was invented in the late 1940s, and was already used in the early 1950s.
Still, despite not knowing when production of these kinds of blanks started, I would guess they weren't developed as early as 1952, so I would really expect that numbers '27' up to 'X' (with 'X' being a mystery, but at any rate below '63') will not be encountered; or at least not until 2015.
Cheers,
Olafo
