12.7x81SR "Ma 103" HEI Projectile


I have an odd two piece projectile. The length is approximately 46.7 mm. The dia just above the grooved cannelure is approximately 13mm. It is approximately 12.7mm on the grooved cannelure. The body section takes a magnetic and appears to have been drilled out. The nose screws into the body counter clockwise and is non-magnetic. See photos which show all views and comparison to .50 cal bmg ball round.

Any ideas?



This should be a Japanese 12.7x81SR “Ma 103” HEI projectile.


Wow! Thanks! This was up for less than 5 minutes. Can you post a picture of the Cartridge case or a loaded round?



And here diagrams from the “Japanese Explosive Ordnance”:


That looks more Italian than Japanese to me


The story of the .5" Vickers and the various uses of its 12.7x81SR export ammo (which led an exciting life!) is here: quarry.nildram.co.uk/Vickers.html


It looks very much like a 12,7 Breda because it is an improved Copy of the Breda HE-I round…which the Japanese used quantities of in 1941-42 as well, usually mixed with Japanese Production…I Have BPD 37 and BPD 39 recovered from Japanese Aircraft on Pacific Island beaches mixed with 1941& 42 production Fuse bodies ( small stamping on fuze cap ).

It is usually assumed that the Japanese used mostly Italian-made Breda ammo during the Pearl Harbour Attack.

Note, thread on the Fuze cap is LEFT-Hand.

Very nice development of the Original Vickers .5 Export Cartridge (Semi-Rimmed).

But under-Powered wrt BMG .50, for range…the HE-I made up for that in effectiveness. Ball was hardly used by the Japanese ( for training);
Combat Aircraft were loaded 5 HEI, 1 Tracer.

Doc AV
AV Ballistics.


The Japanese version of the 12.7 m/m Breda was exclusive to the Japanese army air force, so wasn’t employed in the attack on Pearl Harbor, which was an IJNAF operation. Those naval aircraft were armed with Vickers and Lewis MG’s in 7.7 m/m rimmed (.303) and the short version of the 20 m/m Oerlikon auto cannon cartridge. Jack