Mystery 30mm DEFA/ADEN(?) projectile

Hello all!
I originally had this round a little over 2 years ago, and ended up selling it to a friend in the US, and he happened to be selling his collection and I ended up getting it back from him recently!
I was never able to get and ID on it previously so thought I would give it another shot.

It looks like a typical 30x113mm DEFA or ADEN TP projectile from the outside, however it has an odd steel disk crimped into the bottom. When tapped it sounds like the disk is very thin, which I would guess means there is something inside. Body is made of steel, aluminum windshield and 4 even punch crimps holding in the disk.
The only markings are “INERT” in white ink on one side and the numbers “157 S 000” stamped faintly on the projectile body.

Possibly “blind load” projectile, or a weight inside to simulate the correct weight? Would be great to get an ID or country/manufacturer origin.
It originally came in a typical British brass 30x113 ADEN practice marked casing but it could very well be the wrong case.

Thank you very much,

Rhys, the disc is most likely a measure to cover the projectile base so it can not crack from gas pressure and flames can reach a HE load. A big issue in projectile design.
The disc is usually made of very soft steel.
That it is used on a TP is due to the fract of use of HE projectile bodies which just get inert loaded and then make up for a TP.
Also seen on much larger calibers like on US made 105mm M1 HE projectiles and many others.

Alternatively it also can be a cover for a missing tracer plug.

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Thanks EOD for the reply!

That makes sense, seen a few of the covers on various rounds like 105mm projectiles like you mentioned, or WW2 era French 75mm artillery rounds as well. Interesting as I have never seen one on a round this small, my other DEFA HE round has a typical base on it.

Any idea of a possible manufacturer? Seems like thats the hardest part to pin down with so little information!


As for the manufacturer it is a bit difficult but the soft iron driving bands are limiting the possibilities.
I think you would need to talk to a medium cal expert or designated 30mm ADEN/DEFA collector who can run comparisons on his specimen.

Some 30mm ADEN/DEFA have reverse steel cups inside their hollow bases (like German ones). Sure some other’s have as well.
Did you maybe check the book of Claude Jacquinet?

I have found an image in my files (source: internet).
Derk Harms (NL) made these cutaways. The #8 and #14 also have the reverse cup, to what I see #14 is FN made.


I also see I have an image of a German DM18 TP with this cup:

This is already much farther than I have gotten in my hours of searching!

That book is also new to me, I will have a look through it however I suspect this is not a DEFA or atleast not French made round because of “inert” and not “inerte”, but that doesn’t rule out export rounds of course. Thank you for the link, I have started a small selection of various ADEN and DEFA rounds so more reference is always welcome.

Tapping on the disk seems like it is hollow behind the disk, so could be a covering into a cup or into the empty projectile body. If I had 2 I would be very tempted to take the disk out however I wont be doing that with this one.

Question is, if its just a cup why cover it? Also might have to see when my next dentist checkup is, see if I could get an x-ray of it…

Base covering disc:
It is always difficult to say as for the whys and the hows as the only answer is known by the designer/developer.

Very true, some details are nearly impossible to know.

Ill see when I am at the dentist next, known him for all my life so im sure he wouldnt mind, might be awhile though!

Right, you better know your dentist well before you ask him such a favour. :)
Mine asked me last (and 1st) time about 3 times if all was safe but as he knows my job he trusted me.

I just wonder if dental x-ray machines have enough power to do this kind of job.
We shall see then.

Hehehe yes would be awkward to have a “walk in” for that!

I was also wondering if the steel would be too thick, we shall see indeed!