Cracking the 'F': The mysterious 'F' on IJA headstamps expla



Hold the press!
Here’s an incoming bomb shell for the collectors of Japanese artillery ammunition!

Did you ever wonder just what that mysterious letter ‘F’ means that can be found on many IJA headstamps?
Well, so did I! Enough so to have made it a bit of a personal mission to get to the bottom of it.
It has taken many years and quite some effort, but on March 1st 2015 precisely that was achieved when I finally learnt the true meaning of that letter!
Read all about it in the article that I wrote about it.
The article can be downloaded in full from my website, from this specific page:

Enjoy! I know you will…

PS: I tried posting this article weeks ago here, but the forum then crashed and it took a long time before it was available again. For that reason, you may already have seen this article posted by me on other Internet forums. The information is too good to not share it over here too though, so even though I didn’t get the chance to do so directly after writing the article, I still hope it is enjoyed and appreciated. :)


Very Interesting article, especially the Kanji research for exact representation of “Iron” and “Steel”.
I wonder if this also applies, in Practice, to the German “Eiserne-Hulse” (copper washed Iron cases of WWI…Given the German punctiliousness,using Eiserne (Iron) rather than Stahl ( Steel), would, as in the Japanese situation, relate to the actual chemical composition of the Metal used.

Iron comes in two basic forms, Cast and Wrought–physical states depending on the crystalline structure and means of manufacture. Given that Eiserne -Hulse were drawn and punched, they were “Wrought” Iron sheets as a raw material. Iron, by definition, has no or very little Carbon content; any Carbon present is found as discrete Globules within the matrix of Iron (Fe) atoms.

Steel, by definition , is an alloy of Iron and Carbon in various Crystalline forms, with properties varying according to the Carbon Content. The SAE (US) system gives a good Idea of the Carbon content…Four digit number, first Digit: type of steel. Second digit: Principle alloy other than carbon; Third digit and fourth digit, Carbon content as Hundredths of 1 Percent.

So, SAE 1020 is a Carbon steel, no other major alloying material, with 0,20% Carbon…a Low grade or “Mild steel” ( Re-bar, Hardware store steel bars and Pipes, etc.)
SAE 1035 is a medium alloy Carbon steel, with 0,35% carbon…very suitable for Case Hardening, good machineability, tough…what basically was used in Mausers and Arisakas. ( small impurity percentages (such as in the Swedish ore used by Krupp for Mauser) improved the quality of the common steel.
SAE 1055 – lowest Grade of “Spring” steel…used for Cartridge clips, etc. SAE 1085: Used for making springs (leaf and coil) Hardenable and temprerable.

Steel cartridge cases made in Germany before and during WW II, and after, are made from a SAE 1025-1030 type Mild carbon sheet steel, the same as used for Automobile Body work…and was also used to make the MP40, and MP/Stg 44s etc. It is easily punched, pressed and drawn, and welds easily.

Interesting how the “F” indicator of an “Iron Brass” ( there is also a “Leaded Brass” with similar improved machineability) in Japanese Ordnance Practice has got me thinking about German work in the use of Iron and Steel in cartridge Cases.

Congratulation on the deep research required on the Japanese information. It seems that the infamous “Fire Storm” raids of 1944-45, didn’t destroy all the archives…

Doc AV


[quote=“DocAV”]Very Interesting article, especially the Kanji research for exact representation of “Iron” and “Steel”.


Thanks a lot for your nice words. :)
I really enjoyed the explanation you gave on the grades of steel.
As for what you ask and tell regading the usage of iron vs. steel for cases, there is an interesting new bit of information that has come to my knowledge after first mentioning this same article of mine on the Japanese Gunboards. My mate Takehito Jimbo (a native Japanese speaker who lives in the USA and is fully bilingual and very knowledgeable about such technical terminology) wrote (a.o.) the following to me:

“The word “Testu” used by the Japanese technically is a word for iron, but
sometimes it is used in a bit more broad term that would actually encompass
steel. To be specific, technically steel is “hagane” in Japanese, but that
aside, the daily use of the word for steel is “tetsu”, so there is a bit of
an overlap in usage there. It may give you a bit of insight on the use of
the word tetsu in Japan.”

This makes a lot of sense. It looks then like the Japanese cases may indeed be steel after all…
I hope that Tatsuya Yamamoto has some documentary references about this. It will take a while before I will know this, but I shall ask him that question.



Now that you mention “Tetsu” as the Japanese Word for “Iron”, it takes me back to my Medical school days in Turin, Italy (1970s) where, for relaxation, I tried to teach myself Japanese, using the “Teach yourself” books and a large pile of " Tetsu-do Mokei", one of the most popular Japanese Model Train Magazines ( I was given about 100 copies, by a Gentleman who had spent several years in Japan as an Italian Diplomatic service employee.)

Tetsu-do translates as “Iron Way” or “Iron Road” ( Tetsu=Iron, do= way,road,)…word coined in the 1860s, when “Iron” railways were introduced into Japan. The combination is the same in most National languages ( Ferro-Via, Eisen-Bahn, Chemin de fer, etc.). At that time, most Railways used Wrought Iron, both for Rails and Locomotives…it was only in the 1870s and 80s, that Krupp pioneered quantity steel making, and applied the use of Forged Steel to Locomotive Wheel Tyres, ( the Krupp symbol is three interlocked Wheel tyres.). From there, steel replaced Iron in the construction of Railway equipment, rails and rollingstock. But the “Iron” Name stuck to the Railways. That is also the situation in Japanese. something “Tetsu” may be truely Iron, or modernised into “Steel” in common Parlance… but I think in technical materials, the distinction between “Tetsu” and “Hagane” remains.

Doc AV

BTW, I never got to really learn Japanese…just the Basics ( Character and syllabary (Kanji & Kana) recognition, Language sound recognition, word structure, Good Mannered greetings, some technical ( Ordnance and Railway words) terms.)