13.2x99mm Japanese Hotchkiss "Y 13 2-III"

This looks like .50cal, but I am at a loss about anything else. Who made it? Why is the primer that way? I do not hear any movement of gun powder when shaken.

13 = 13.2mm Hotchkiss
2 = 2602 = 1942
III = september-december
’y’ = To = Toyokawa
"Japanese Ammunition 1880-1945, part 1, Ken Elks"

Merci boncoup. Do you know what happened to the primer? The neck measures the same as another un-fired round, the projectile seating feels original.

The primer looks as if it has been fired using a punch. I suspect that this round has been “pulled”, the powder dumped, the primer fired, and the projectile reseated.


That has to be the heaviest annular primer crimp I have ever seen!


This was used only by the Japanese Navy, originally in the Type 93 AA gun (a licensed copy of the Hotchkiss) but later also in the 13mm Type 3 aircraft gun (a copy of the Browning). Not to be confused with the Navy’s 13mm Type 2 aircraft gun, which was a copy of the Rheinmetall-Borsig MG 131 in 13x64B calibre, only with percussion rather than electric priming…the Japanese are to be commended for providing such an enjoyable variety of guns and ammunition to delight and amaze armament historians!

I found this picture at this very nice Japanese ammo website japaneseammunition.com/start … lude_id=17. Was this method of primer deactivation by hitting it with a punch bit somewhat common or it is just a coincidence?
I guess these cartridges are lucky not to share the fate shown in this photo,