This was a Jeffery & Co. development in 1903 as a smokeless alternative to the 4 and 8 Bore Black Powder rifles for use in Africa.
The first two specimens were made by BELL, with the last one by Bertrams Australia as a commemorative for Deutsche Waffen Journal
The specimen third from the right is a commemorative cartridge made for the 1994 IWA show in Germany for one of the sponsons, Verband Deutscher Buchsenmacher und Waffenfachhandler.
Written on the cartridge: 600 NITRO Hand made by Bill Ballard, Billings Montana
This is the rarest of the 600’s as the Jeffery version was one the earliest together with the 2 no-headstamped variations above.
The first 2 specimens are the Monolithic and “Dead Tough” loads by A-Square.
Below is the box with sample cartridge by BELL