Cartridge case identification

I have three fired cases given to me by my late grandfather who saw service during WWII, I suspect they are very common calibres from the period and i think i have correctly identified them, but i would like confirmation from those more knowledgable than myself, so here goes…

from left to right in the above photos;

case one;
case length: 108.5mm
neck diameter: 20mm (approx, neck is distorted)
case diameter: 25mm
rim diameter: 22mm (rebated, rimless)
berdan primed

case two;
case length: 99.3mm
neck diameter: 12.8mm / .50" (approx, neck is distorted)
case diameter: 20.3mm (rimless case)
boxer primed

case three;
case length: 80.1mm
neck diameter: 14mm / .55" (approx, neck is distorted)
case diameter: 18.4mm (rimless, tapered case)
berdan primed

I’ve added a .303 case as an indication of size

I think they are 20mm Oerlikon / .50 cal browning MG / .55 Boyes anti tank

how far off am i?

could someone please confirm identity and post photos of the complete rounds?

also an indication of some of the headstamp meanings;
on the first round, does OeZ indicate Oerlikon and nitrocellulore propellant?
second round, whick manufacturer is RA?
third round, B.I.Z? (on .303 I’d take this to mean Incendiary Mk I, nitrocellulose propellant, is the same system of marking used on larger calibres?)

No 3 is a English .50 vickers.

Magpie your assumptions on No1 and 2 are correct.

second round, whick manufacturer is RA?[/quote]

That’s Remington Arms Company, USA.

many thanks guys!

does anyone have photos of complete rounds?

The British marking system for small arms calibres up to 15mm was the same for all calibres, so your .50 Vickers is an Incendiary Mark 1 with Nitrocellulose powder, made at the ICI Kynoch works in Witton, Birmingham in 1942. A complete round would have been loaded with a GM jacketed bullet. Here is a photo from This is the same round as yours but made in 1943.

The 20mm Oerlikon was made by the Newly opened Ministry of Supplyfactory at Radway Green in Cheshire in 1942. In 1941 this factory used a broad arrow marking instead of the letters “RG” to disguise the location of the factory if any of the ammunition fell into the hands of the enemy. This factory is still there today, modern 5.56 and 7.62 ammunition are still made there.

Here are some .50 Vickers, l. to r.
Ball IIz
Tracer G Iz
Incendiary B.Iz

I do not have a picture to hand of my British contract .50 Brownings made by Remington but here are some wartime drill rounds.

I do not collect 20mm so some-one else can post a picture of the Oerlikon, but you are correct about the abbreviation OeZ.


I hope these photos will be of assistance

4 & 5, from the left, are what your 20mm looked like before it was fired Tthere is a thread where the weapons operating system was discussed in great detail, and it explanes how/why the cases look so different, before and after {very interesting reading)

2-9 are various 50 BMG, #13 is the 55 Boys (note the belted case). I’ve been told that # 15 is the 50 Vickers High Velocity (12.7x120SR)

Thanks again guys for the info and photos.


in my .303 collection i have rounds with both one and two broadarrow marks, I have been led to believe that one broad arrow denoted RG (as you have stated) and two broad arrows denoted Spennymoor (later SR h/stamp), is the correct?


would you have a link to that thread? sounds very interesting.


You are right, one broad arrow is RG and two is Spennymoor. Be aware that on early .303 ammunition (pre-1910 or so), There are sometimes one or two broad arrows over stamped onto the headstamp. This denotes government ownership, and is found on ammunition made by civillian companies such as Eley and Kynoch on contract for the military.

You should contact TonyE about a copy of his book “Headstamps and Markings on .303 inch British Service Ammunition”. It is really worth owning a copy if you collect .303s.

Hi Falcon,

thats what i’d thought ref RG and Spennymoor and i was aware of the broad arrow overstamp on early rounds although i think i have one from 1912 or 13, cant check my lists at the moment, as I’m staying at my girlfriend’s (who incidentally has a copy of Tony’s book on my christmas list)



Link, perhaps this one … nnon+naval
I wasn’t going to go through all 15+ pages

Another one … m+oerlikon
Page 3 has some detail photos of the breachblock

thanks tailgunner,

that’ll give me something to read over coffee break tomorrow!

There bare some nice pics of .50 Vickers ammo (and the closely related 12.7mm Breda), including sectioned ones, in this article on my website: