Btitish Cartridge ID needed

Hi; Can someone give me an ID on this cartridge. It is a bottle necked centerfire with a paper patched express bullet;
NECK-------- .606

If by Express bullet, you mean copper-tubed hollow point, I’d say it’s a 20/.577 Alexander Henry. George Hoyem’s volume 3 shows it with a double struck headstamp.
But I’m no expert!

Thanks for the I.D. Sam. Do you have any more info on this cartridge? It is not in any of my books. The cartridge is off an old Eley Cartridge board.

This cartridge was developed by the famed Edinburgh gunsmith Alexander Henry about 1890. Henry was noted for his fine double rifles and developing the rifling system used in the Martini-Henry rifles.

Henry necked a 20 gauge shotgun shell to .577 with a case length of 2.75, thus the cartridge is called 20/.577 or .577 Alexander Henry.

Eley offered both a solid lead bullet and the PP copper-tubed hollow point bullet. I believe that Eley only used black powder while Kynoch had both BP and a light cordite loading. IME, the Hoyem double strike h/s is rare.

Eley lists this round in their catalogues from 1893 to 1905.