Interesting 27.5 mm apt-d round (sectioned)

I was fortunate to acquire this interesting 27.5 MM APDS (correction: NOT DS) round. I have learned it is sometype of experimental aircraft round but know very little about it. Does anyone know anything about it? Their is no headstamp markings and no markings on the sub-projectile, sabot or driving band. It looks factory made with the projectile securly crimped to the case. It does have what appears to be a fired primer and their is some type of filler that sounds like powder or lead shot? You can hear it move when you invert the shell. It is pretty heavy. Stenciled on the side, it reads:

P/N 7200827
AOMC LOT 1 - 1

Would you tell us the case length?

Is that your hand? Looks like someone shoots a lot of lefty pistol. Perhaps a High-Power, PPK, old 1911?

EOD: My calipers do not open big enough but using a regular ruler, it measures 6.5 inches from headstamp to case mouth.

Jon, to funny! I have shot my Dad’s PPK a few times and ofen get cut by the slide, but on my right hand. The small, “Boo Boo” on my hand is a healing wound from a 8.5 foot Crocodile Monitor lizard (similiar to the Komodo) that stuck a claw in me and not shooting related :-)

Ouch!!! I think I prefer hammer-bite!

You have a dummy of the second and final version of the 27,5mm “Bushmaster” cartridges.
This single barrel machine guns name is GE-127.
The ammunition was developed by Aerojet General Corporation.
There are 4 rounds HE , APDS , and simulation for both.
Read more in " The Machine Gun volume V " by Colonel George M. Chinn.

Thank you Rien for that information and for taking the time out to e-mail me that fantastic document on the gun platform. I realized I made a mistake with my original post. It turns out that the projectile on this round is NOT a sabot. I have learned that the whit composite surrounding the penetrator does not discard but instead travels to the target were it is sheared off on impact.

I was able to unscrew the primer and figured I’d share 2 pics. It appears the shell was filled with dried grains of wheat. I emptied all the wheat out so I could shine a penlight inside. The shell case seems to be unfired but the primer is. The primer has a impact mark and the long rod has a blow-out at the base. I replaced the wheat and put the primer back. I have also learned the the “D” in “APT-D” means “DUMMY”.

This pics shows some of the wheat used for weight I’m guessing.

FYI: I corrected the title of this thread. I original thought this was a DS round and it is not so I fixed the title :-)


Could not resist and had to section this round. The white plastic, “Sabot Type” component is made from some type of plastic or resin and was attached to the metal core with a strong glue. It is one piece and had no pre-fragment lines or grooves anywhere.


Close-up of the projectile without white plastic part.

I scanned the base of the projectile to show a super tiny hole in the base plate. I am guessing this is for the tracer to ignite but not sure.

How rare is this round? I have never heard of it. I would never be able to bring myself to section something like that.

Falcon, I am guessing they may be rare, but do not really know to be honest. I bought 2 of them which is one reason I found the cahonies to section this one. Also, the design & function of this round was just driving me nuts. :-) I have never seen them availible other then these 2 specimens but that really does not mean much. I still would like to section the base of the projectile but need to study it more before I attempt it.


1 more pic to show how the core is attached to the base of the projectile permanently. I think it was “Pressed” in hydraulically?


Quite rare , about 10 known.

This fellow is a real scholar of ammunition. He is not just a “collector” .

He definitely made a good job of it, I’m not denying that.

But if I was going to do it I’d be cautious of something going wrong.

Trust me! I was cautious and nervous about cutting it in case I ruined it. Their is always that risk for sure. :-)