.303 British Mystery Round Revisited

So around last year I posted a picture of this same round and asked anyone if they knew anything about it. It’s a 1943 dated case marked K5 BVIIZ which led me to believe it was an incendiary round, but I had never seen the BVIIZ cartridge loaded with a non copper jacketed bullet. Some people responded and said it it’s probably incendiary, some said it was probably a reload due to the small gashes in the side of the projectile that could be from a bullet puller. There is left over blue paint around the primer, there is also the remnants of dark blue/purple paint around where the bullet and case mouth meet. It still retains the original nitro cellulose propellent, as when shaken it can’t be felt. The projectile is magnetic, and the entire round weighs about 385.809 grains. I read somewhere that the British Military originally loaded their incendiary rounds to look like ball rounds to keep them secret. Could this be an example of that? I also thought this could be an older incendiary bullet that was pulled from its case and reloaded into a new case for the war effort due to the blue paint around the case mouth. Or just a ball round reloaded into an incendiary case? Any info helps. Thanks

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Unfortunately, I think the only definitive options are pulling the projectile or getting an x-ray. I wonder if the neck sealer is loc-tite (or similar).


The British .303" B Mk VI incendiary was indeed loaded into unmarked cases by Royal Laboratories but only during the initial stages of its introduction. As far as I’m aware all of those early bullets were GMCS and not cupro-nickel. The latest British .303" Incendiary loaded with a cupro-nickel bullet that I can find with this profile is dated 1927. 1943 British production should have a GMCS bullet. The pink colouring visible at the casemouth looks very Japanese to me and I’ve certainly not seen this colour on an original British cartridge.

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The picture doesn’t really do it justice it’s more a dark blue almost purple. Perhaps some sort of Japanese ball reloaded into a surplus .303 case? They both use a .311 bullet so it isn’t too far fetched. I’m just curious as to why they’d keep the original propellent charge and primer if it was a post war reload?

Also there is what could be a very, very slight crimp on the case mouth. If it is a crimp it’s very slight, it’s almost unnoticed without really studying it, if that helps at all.

after looking at the marks on the side of the bullet, it’s becoming more apparent that the bullet was pulled. They are two small symmetrical marks where the material of the bullet seems to be pushed up towards the tip, so it makes sense. I really want to try and remove the bullet, but i would have to do it with another empty case and i don’t want to ruin what may still potentially be a cool piece of history. Any thoughts?


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Given the slight chance that it is some sort of incendiary round, would a kinetic hammer set it off?


Discussion of inerting / dissembling a possible Incendiary round should not take place on this forum.

Please remove your posts.

See the forum entrance page

“Any matters of safety, proper ammunition for use, loading or reloading of ammunition must be resolved by consulting qualified gunsmiths, firearms makers, or ammunition makers.”

Thanks for the help guys. I’ll get an impact bullet puller and try the methods suggested. I’ll post an update after I get it all disassembled to hopefully finally solve the mystery!

The reason of safety exists with INC rounds is that they often use phosphor as an igniter. Some rounds have a lead solder seal in them which lets air in to ignite the phosphor after leaving the barrel, others used internal methods. IF what you have is an INC round you & could be in danger. Get an X-ray.

I would advise you to read all you can about British INC ammunition.