Help me identify this cartridge


I ran across this and have had no luck researching it. I know it is a 25MM bullet because I had a collector measure it. The entire length is 9 inches, I’ve include some pictures I hope will help.
Thanks, Shannon


I think it is a Hotchkiss 25mm x 163 Type 96 used by the Japanese Navy.


Armourer, would that be from the WWII timeframe or earlier? Thanks for the help.


Yes, this is a 25x163 Rimless Hotchkiss anti aircraft round. Funny that I have bought one as well today and posted photos of it. Someone else can probably give you more information. Here is my round:


The Japanese built version was adopted for service use on 6 August 1936.
More info at


I’m new to this type collecting but, your round is a German and mine is Japanese. Did both armies have some of the same rounds? How by the markings on mine would I be able to tell the date? Does yours have the set screw and the I A F L settings located on the second ring from the top?
Thanks, Shannon


Wow, that answers a lot of my questions Western. But I’ve got a few more after reading that info. First is there a way to tell what type round this is without pulling it? I don’t see any color that would identify it as AP, tracer, Ind, etc… Also, this is proberly a stupid question but if this round has a bursting charge like the info said, could it still be live. Again this may sound stupid but dit this type of shell explode on contact?


The Japanese Navy bought this weapon from the French. Mine was made in German occupied France on French machinery, and stamped with the German Eagle over a number on the case and projectile.

I (think) the date yours was made is 1943 (the 17th year of the “Showa” era, which wa the 17th year of the reign of Emperor Hirohito). I think that is what the S next to 1 over 17 means. The anchor indicates naval use and the Japanese characters are accpetance stamps (means the round had passed quality control).

Don’t be surprised if I’m wrong on any of this as this is way out of my field, which if anything British military 20mm and below, but I have many other bits (Like my 25mm Hotchkiss round) that I bought because I liked.


Shan, I’ve seen a number of these rounds, and most of them have obviously demilled (usually by burning a hole with a cutting torch through the case). Usually, they would also remove any bursting charge and/or detonator at the same time (Japanese explosives weren’t known for their stability even when new). These rounds would’ve originally been marked as to functional type (tracer, HE, explosive, etc.) with a coloured ring around the neck of the case, but this is unlikely to have lasted this long if it’s been handled much. Is there anything loose inside the case? If not, that’s one good indication that it’s been inerted. Second, is the projectile still crimped into the case, or has it been spread at all by pulling? Finally, on the vast majority of these rounds, you can simply spin the nose fuze out, and the spot where the detonator would have been (inside a thin metal tube) will be empty.


The original owner did drill a hole and empty the powder out. The projectile is still crimped into the case and has not been disturbed. There is no spinning the nose fuze out, I figure someone did take the detonator out and then glued the fuze where it couldn’t be taken off.
Thanks for all the info.


Shannon–You may be correct that the projectile has been inerted, but until you are POSITIVE, handle it as through it is still live.


This is the standard Japanese Navy AA shell for their sing, double and triple Hotchkiss Gas operated AA MGs (Box magazine fed).

TO Note: Japanese Fuses for the most part (12,7, 20mm, 25mm) are LeftHand Thread, so “unscrewing” them the "normal way will only tighten them up…Unscrew in the opposite direction with the proper wrench.

Exploding charge in Japanese shells of this type is usually RDX, with a simple Berdan-type cap detonator, hit by a striker which is protected by a centrifugal arming safety. (Shell spin causes safety to “spin out”, unlocking striker, which on contact, detonates cap which sets off “Gaine” and then main bursting charge.
To ensure the fuze cap does not “spin off” during firing, the thread is “Left Hand”.

Cartridge case is "Showa 17-1 ( Showa year 17, month 1 (Jan. 1942); Naval manufacture & issue (Anchor).
There should also be dates on the Fuze itself and inspector’s mark “To” (looks like a stylised “t”).

Doc AV
AV Ballistics.


Which way does the thread on the French rounds go? Where would I get hold of the proper wrench to remove the fuse in mine? All it has are 4 tiny point marks at 90 degrees to each other around the base of the fuse that appeard to be the only way the wrench could grip it. It would almost certainly be inert to have been sold at a market in GB, but I would like it if the projectile was “fully strippable”.