Eley along with Kynoch developed the .404 cartridge, the earliest known drawing (Eley No.24) of the cartridge was dated 18th October 1905. The dimensions on this drawing match those on later drawings by Kynoch, Eley again in 20th January 1908 and later Kynoch and ICI Metals drawings.

The Eley 404 Rimless back in 1905 is just the standard .404 Jeffery cartridge as we know it today.