Need help identifying a strange round

I have had this cartridge for many years and have been unable to figure out anything about it.
The projectile is magnetic and appears to be turned. The pic shows a 9mm parabellum for size comparison. Micrometer shows the projectile in question is 8.96mm at the case and the case itself is 9.51mm while the parabellum case is 9.65mm. Case length is 60.325mm (2 3/8"). The primer has ICI stamped on it consistent with the Imperial Chemical Industries trademark. There are no head stamps or other marks other than on the primer. Overall weight is 15.5 grams. As seen in the pic there is no rim nor is there the typical groove as found on “rimless” ammunition.
Thanks in advance for your help. Unfortunately I am oly allowed one image.

Hello Kevin, welcome to the forum.

You have a classic collectable cartridge designated “Cartridge SA Ball No. 1 Mk. I” or “Cartridge No. 8 Anti-Personnel Switch Mk I”, but commonly known as the “.40 Booby Trap”.



Though I do not know why people do call it “boobytrap”. Must happen when ignorant folks (journalists?) make up names for something they do not know.

The round is part of a British AP landmine:

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I think people call something like this a “Booby [an awkward, foolish, or stupid person] Trap” because “Land Mine” is equated with a fairly large explosive content, and a “Booby Trap” is usually intended to injure or kill only one person, (not to be confused with a large/long pit of Punji sticks dug next to a trail).

Jack, not really.
Mines are mines and boobytraps are a different thing.
But as said, people are having opinions and are often mistaking these for knowledge.

I was just attempting to answer your “… why people call…” query. Valid answer.

You guys are awesome, thanks for the info.
I have been lurking on this site off and on for several years and was pretty certain you guys would know what I had.

In England it’s most common name is probably too rude to mention on here but it is a crude reference to it causing one ‘to losing their testicals’