Japqanese WW11 ART. CASE?

Any help with type of shell and headstamp info will be appreciated.
thank you . Terry. Big picture to show writing!

Yes, Japanese. The crossed cannons on the casing and primer indicate Osaha Arsenal production. For more info one possible source is: japaneseammunition.com

Dimensions in millimeters would also help i.e. rim diameter, case length and case mouth diameter.


The primer and case are date stamped Showa 17 = 1942. there was a thread about a year ago discussing the “F” mark. I can’t recall if any conclusion was established as to the meaning of the F mark.

japaneseammunition.com/start … ub_cat=196
Speculation on the “F” mark.
edit for additional content.

Thank you gentlemen, Do not have case, belongs to a friend who collects anything WW11 Japanese or German, just dropped in as he was passing and ask for help to identify. Approximate size case about 30 centimetres long, rim diametre about 80 centimetres, will check the correct sizes at a later date, but your help with marking appreciated. Terry.

Could the mark be a “quality control” inspectors mark. And the mark is to show that a batch of ammo is OK, which is why it’s not on every round.