30x111B ADEN unknown ID

Who can identify this 30x111B Aden loading? I know SWN and RG.

Black projectile with red band.
SWN LOT 20 / 56
30MM RG 56
OOO. three circles touching on the body. (Unified threads?)


You’re correct - three contiguous circles denotes a Unified thread.

I have never seen that before. Headstamp markings on the belt and in the extractor groove. Also I am a tool maker and did not know this about the 3 circles and unified threads
Thanks for showing this.

Tim, what exactly was the difference to non unified threads then?
What was used before?


Prior to the introduction of Unified threads, we (the British, Dominions and Commonwealth) had used Whitworth thread form (55 degree thread angle) and almost all of the threads irrespective of diameter, were of 14 tpi (threads per inch.) Post war, in the early fifties a decision was made to adopt the American Unified thread form (60 degree thread angle) which one could view as an Imperial version of Metric thread form (it’s a bit more involved than that). The switch was not just ordnance, but British engineering in general. With respect to ordnance, the adoption was over a long period due to need to maintain compatibility with the vast stocks we held. I suspect there is still ordnance in British service that still uses Whitworth thread form. I have a very late No. 117 fuze (25 pounder) of very late 70s vintage that is threaded 14 tpi Whitworth thread form.

As a means of indentification items with an Unified thread form were stamped with the three contiguous circles. I think towards the late 70s early 80’s we at started using metric thread form on ordnance items.

It may interest you to know the primers on German artillery cases up to the end of WWII used a Whitworth thread form.


Tim, thanks for the clarification. I was not aware that there was an issue between the inch threads before.
Were also other items marked with the 3 circles. Like fuzes for example?
And when they switched to metric was there also a special marking?

And as you say, the German priming screws were Whitworth and so were some navy fuzes which then had a “W” stamped on them to indicate the different thread.

I have also learnt about unified threads.
I remembered something about the circles on my 105mm FD How. and 105mm brass Leopard Tank cases meaning unified threads but did not fully understand the meaning.
I do not think my other 30mm shells have this marking. Will have to check. Cheers. Ron.

In the 1920s British Ordnance adopted British Association (BA) threads for small arms. BA threads were used on the No4 Rifle, No2 Revolver and Bren LMG. Were BA threads ever used on artillery fuses?

what the type of projectile loaded on this 30x111 aden ?


Fuzes – no, but this is where the problem of mixed threads is most likely to manifest itself as some shells are supplied ‘plugged’ for the end user to fuze. The ‘L’ series fuzes with an Unified thread were generally 2” 12 tpi, which is all too close to the G.S thread of 2” 14 tpi (Whit’). Perhaps the Ordnance Board considered the probability of mismatched fuze threads negligible, but why mark the primers as there is no chance whatsoever?

Metric - I’m guessing as it’s out of my timeframe, but I think by the time metric was being used, the inventory was substantially smaller and only came as a complete rounds and thus not necessary to denote the thread nature.

I was totally unaware about the naval fuzes – thank you.


I think the marking on your projectile is rather unnecessary, as once assembled it was not intended to be unassembled and as far as I’m aware they were only utilising Unified thread on the Aden. Marking on the cases slightly makes sense as they would be returned to the factory for refurbishment and a fresh primer. However, the ‘L’ series primers which were the first to use Unified thread form have a diameter of 1.25” (the early ones) which is too big to fit into any of the Whitworth primer pockets. That said, I’ve had the misfortune of working with some people who could defy all odds and do it.


BA threads on artillery fuzes – I’m afraid I can’t answer that, I don’t know.

Come on you experts on identification.
We have side-tracked to learn all about unified threads but forgotten to answer my first question. What is this loading? Surely someone has a similar one? Black must surely be AP which I doubt with a dummy? fuze or maybe Practice Tracer which is another guess.
It is original and still loaded. Why black with a red band?

For that vintage black is more likely ball/practice,though i’ve not seen those with pinned 'fuze’s.
I can’t find any reference to 30mm Aden having a tracer round except for some experimental radar shells.
Is there any other stamping on the belt ?,later mods usually have the loading marked on it,ie PRAC.

It has no extra markings. I have the later Proof, HEI, Drill, Prac 2Z & Prac 4Z which are all stamped on the belt to identify the loading. This one has me guessing.
As an extra question, I have one fired case J.30MM.RG 01 with 01 GD 006 on the belt.
So this is also an unknown loading to me. Any thoughts?


What is the case length? (your last post)

J.30MM.RG.01 is another 30x111B ADEN.
I had not seen one from 2001 before and does not have the usual load on the belt.
Looks like Lot 006 filled by GD. Who is GD?
Is the 30mm ADEN still being made and used?

GD - Glascoed, Monmouthshire. Our only remaining filling factory.