I recently obtained the 37mm shown from Japan. Rbt. Mellichamp says it is previously undocumented. His volume 1 on the subject of 37mm ammo has been published and is a MUST BUY for serious collectors of big bore.
I identified this case as a 1 1/2 pounder Vickers Aircraft cannon but Bob says it is a bit early for that and may be a 1 1/4 pounder Vickers. Both of these are 37mm.
The headtsamp dated 1913 carries the typical British EOC manufacture marks as well as Tokyo Arsenal stars and JM in a cartouche. Who is JM ?
Bob commented that the large “C” is a British inspector mark found on 37mm contract ammo for NORWAY !
Both of these guns are extremely rare. Why this was in Japan; who knows ?