.340 British military revolver ? bullets

On a UK metal detecting forum someone has asked for information about some bullets found on a UK beach.

Diameters measures 8.6mm - 8.7mm (.34”)
Weight is 10 gram (155 grains)

Most have cupro-nickel jackets, some look more copper.

The base on some have a pheon (broad arrow) mark visible.

What are they?

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They look like .380 Mk II bullets.

Fede, I agree, but the diameter is only .34”

Yes, you are right, and they are also missing c. 20 grains, but I think this may have been caused by years of corrosion.

Some feedback from the person that has found these,

Thanks again for the input but I’m sure they are not .380 bullets that have suffered from general corrosion, to answer the various questions.

They definitely still have their metal jackets, the couple of copper jacketed ones came out bright copper coloured although they quickly dull once the air got to them, the majority are presumably cupro nickel and have a reasonable silver appearance which darkened over a couple of days. When you look at the base of them you clearly see the difference between the jacket and the core.

I would agree with you that on first looks they appear to be Mk2 .380”, the profile is very similar, they have 2 rings and they come in both copper and cupro nickel jackets. However I’ve found more than 20 of these that are in reasonably “good” intact condition and few other which are mangled after hitting something. The good ones are consistently the same weight and diameter, there is very little variation in individual bullets and across the group (0.2grams/3grains) which I would expect to see if general corrosion was the explanation. Also I don’t see signs of level of corrosion required to reduce the diameter and weight significantly, yes they are lightly pitted but the features (rings, arrow stamps) are still quite sharp.

Could they be intended for the .340 Tranter revolver?
Was there any military use of the Tranter?

Could they be for the experimental .34B BSA pistol?
The only picture I found of a .34B BSA pistol cartridge has a very different bullet profile.

My 2 pence is they are originally .380’s, I’ve not seen any mention of the .340 ever being used or tested by the Military, although a Officer could have carried one. The .340 was a black powder load, carried over from the rimfire era. Your correct that none of the B.S.A. pistols had an original projectile of this shape.

That the bullet weight is off from the standard, I have no explanation. Perhaps the bullet diameter could be explained by someone who swaged the bullets to .340 to load into his .340 revolver to shoot because he couldn’t find any .340’s?

Thank you Pete. These are proving to be a mystery.

I also doubt that the 340 Revolver cartridge has ever been offered with FMJ bullets

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