The "F" on japanese cases


May be a new thread would be helpful. Lets try to make the problem smaller.

Headstamps are only regarding to caseform, material, alloy, manufacturing.

Mostly headstamps are stamped and could not be changed while reloading ect.,
So any info about charge or projectile would be rubber stamped or painted - so it could be changed or removed easy, if the case would be used several times.

The “F” was only found on “Army” cases? ( or navy and projectiles, primers too)

If we know - only army - only cases - thats a step.

Are there any cases without “F” or other letters?

What is the time frame of “F” cases - only WW.2 ?

Will the “F” be found on steel cases?

If our japanese collectors would be able to have a look at their references or cases to ask these questions?

Best Genkideskan


OK the first results.

Only Army , only cases, only Showa ( 1925 - 1945 ( end of war ).

The “F” is NOT the maker and NOT the date of production.

So we have left -

case construction
special primer pockets

Questions - Headstamp without an “F” or maybe annother letter.
“F” on steel cases ?



Sounds like a good way to proceed.


Notice the F on the top right corner of this British box. What does that mean ?


Looks to me to be "PROVED AT “XXX” degrees F…as in proved at a certain temp. ??



Could be. I can’t tell if that is a degree mark or not.