20mm German

I bought an old German 20mm case which was rusty. Gave it a light dusting on the headstamp with my air abrader. It revealed an extra mark IV which is encircled in red. This mark is punched in the case, albeit lightly. Can anyone identify what it represents? Many thanks Paul

I don’t have a clue Paul but nicely presented photo…and welcome to the forum!


Looking at photos of other German 20mm cartridge headstamps (WW2 time frame, steel cases), the lightly stamped Roman numerals occur somewhat regularly but they are not discussed in any information I’ve seen (which isn’t all that much!).

The closest thread, to your question, that I could find concerning German 20mm headstamps here on the IAA forum is: [20x80mm RB).
Unfortunately the photos of 2 different 20mm headstamps with a small case letter, lightly stamped, located next to the lot number are now missing from the thread so only the discussion remains.
Forum member EOD indicates that the small case letter located next to the lot number in the headstamp is a sub lot designation.

In the few headstamp pictures I’ve seen that show the Roman numerals, the numerals are roughly 140 to 180 deg. opposite of the lot number.

Hi Timeout,

The roman numerals are denoting the ‘Stahlwerk’ (steel manufacturer)

The attached page is out a german publication “Munition der 2cm FlugzeugAbwehrKanone 30 und 38”

Thanks Orphers… now that I know its means something I will give some of my other cases the same treatment. Could not see the mark before I cleaned it. I know “auz” is Polte AG works at Arnstadt where they made 9mm pistol and 20x138mm cannon ammo. The trick is to find out who the marks belongs to, so if you know please dont tell me but just point me in the right direction where I will be able to find out. I have Michael Heidler book on German marks but cant find it in there. Thanks again…paul


I’m not sure if the steelmills for the 20mm are the same as those for the 7.92 steel cases (i guess they are).
You can find those roman numeral steel mill codes here:

Orpheus, in 1944 the steel mill was not indicated in the hs anymore. So the meaning here is different.

Timeout, be aware, “auz” did not make make any rounds here as the hs applies only to the manufacturer of the case. This is very often missinterpreted by too many people who conclude from the hs of a case on the manufacturer of a whole round which is a very different thing. If “auz” loaded any complete rounds it will be indicated on the projectiles by use of paint.

Could the case have been made in 1943, but then headstamped in 1944? Or would the manufacture of the case always be followed very soon after with headstamping / loading?

The normal procedure would be to have the actual date of manufacture in the hs.

From nowadays commercial practices we know (have seen such specimen) of predated hs when a produced lot is to be delivered in lets say 2015 but is made today as production and loading takes some time. So the customer will receive in 2015 ammunition which is also dated 2015 instead of 2014 (we all know there is people who know a jack and can not be pleased in any other way than having it this way).

I am not aware of Arnstadt making any 9 mm, loaded ammunition or cases. I have never heard of an “auz” code on 9 mm ammo. If someone has real documentation proving they made it, or a picture of an “auz” headstamped 9 mm cartridge or empty case, please post it here.

If there is documentation that they made any 9 mm case using only the “P” headstamp, usually attributed to the factory at Magdeburg, please post it.

John…my info came from the book by Michael Heidler…Deutsche Fertigungakennzeichen bis 1945. (Visier Edition) page 99 it states…auz Polte AG/9mm Pist.Patr.08, 20x138mm-Kanonenmunition…Werk Arnstadt (T)
Hope that is of some help…paul.