7.7 (.303) japanese manufacturers

Hi all,
Does someone has a list of the different japanese .303 manufacturers ?

  • “yo” mark, star, bomb…

“Yo” (a reverse “E”) is the Yokosuka Arsenal.
“To” (a little like an upside down “Y”) is the Toyakowa Arsenal.
“A” (like a “P”) is Asahi-Okuma

These are all Navy.

The star is the Tokyo Army Arsenal but these are probably for a Navy contract.


Thanks Tony,
I also have one with a flame or bomb dated 88 (1928); from where is that one?
As far as the dates are concerned, should we always remove 60 to get the date?

  • 7.7 0-111 E; is it for march 1940 ?
  • 7.7 2-1 y; january 1942 ?


Japanese year dates are based on Two systems, the Showa Era year (Showa 1 is 1926) of the reigning Emperor, Hirohito,
and the more ancient dating system based on the beginning of the Japanese Empire (660 BCE), which had 1940 CE as “Year 2600”; So as in “Type 89” (2589) which equated to 1929 CE, etc, and
2599 (T99)==1939, and so on…
Now the “88” date would place that .303 cases at the very begining of Japanese production of .303 (7,7 IJN) ammo…the Japanese during the early 1920s bought quantities of both Vickers and Lewis Guns from Britain, as well as large quantities of .303 ammo from Kynock…by 1927, they had adopted ( Of their own manufacture and specifications,) the T87 Vickers Aircooled and the relative .303 cartridge,(T87), a copy of the British standard Mark VII cartridge.

It is thought that Tokyo Ammunition Factory ( within Koishikawa Arsenal) made the first lots of .303 ammo for the IJN…hence the “flaming bomb” mark…when Koishikawa finally had transferred all its Rifle/MG making capacity to Kokura (By 1936) the Tokyo Army Ammunition Plant adopted the “Circle in Star” Mark on its labelling. BY the mid-1930s, The IJN had set up ammo manufacturing plants within several of its Navy Yards, to better supply its expanding Naval and Air forces…AFAIK, the earliest IJN Made ( headstamped) .303/7,7 is “97” dated ( 1937) .
Other collectors may have earlier dates, to improve information in this area.

Doc AV

Many thanks.
The earliest IJN made I’ve got is also dated 97.

Hi all,
Can someone give me a link on internet to get the manual about japanese ammunition (9-1985-5) in good condition.
I manage to find it but the quality is poor and do not manage to get weight and length of .303 ammunitions.
I try to identify a round with black primer annulus GM bullet which seems to be an AP (magnet) but normally it should be a ball because of the black annulus.
Many thanks

These are the ones in my collection. All the others (Yokosuka, Toyokawa, Asahi-Okuma as well as the no h/s variations from late 1943) have the domed brass primers, but the “crown” variations all have the flat brass primers, There is also a colour variation on the primer annulus from the standard colours. Is it significant in some way?

Two of these variations have just the crown and not a date. Which is older? Also if you look closely, it seems that the ring crimp on the primer was added after the headstamp

I have three of them :
Crown 88; purple/black primer annulus: ball (secured by three crimps)
Crown; red primer annulus: tracer (no crimp)
Crown 88; red primer annulus: tracer (no crimp)

Normally the primer annulus color means:
black: ball
white: AP
red: tracer
green: incendiary
purple: high explosive

I removed some bullets from those one and others and the weights are:
ball: 173-174 gn
AP: 176 gn
tracer: 147-152 gn


The usual practice is to headstamp a piece perhaps two or three (or more? depending on the manufacturer) stages before seating a primer & crimping it. You will also see stab crimps into the headstamps.