ID needed

What is it?
I think this is a 303 British adapter?
Case L. .946"
Head .346"
Neck .312"
Mouth .290"

with that post / base / primer it certainly does appear like a British adapter, but I’ve not seen one with a neck, for whatever that is worth.


Here is a comparison with two adapters.

Bruce, this is a rare variation of the .303 Andrews & O’Kelly practice adaptor cartridge whose design combines features described in several patents assigned to them during 1890, like a “flangeless” case with one projection that enter a slot and connects the cartridge to the adaptor by a bayonet joint, and a case with “reduced diameter” to facilitate removal. I don’t remember ever reading about an explanation regarding the different case diameters found in variations of this same basic design, and their specific purpose. You may want to take a look at Hoyem vol. 3, p. 141.

Its most notable feature was covered in patent no. 15,282 of 1890:



Thanks Fede.

you just have to smile when Fede answers the most obscure question with scholarly detail…who needs Wiki ???