HISTORY
Every rifle enthusiast knows the extensive range of proprietary large-bore, low-pressure nitro rifle cartridges developed by William Jackman Jeffery, with some of the best known being the .450/.400 3” Nitro Express (also known as the .400 Jeffery), the .404 Jeffery, the .450 No. 2 Nitro Express, the .475 No. 2 Nitro Express, the .500 Jeffery and the .600 Nitro Express. These cartridges were all based on Jeffery’s very successful formula of using a long, wide-bodied, very strong case with a thick, heavy rim. The thick rim and case dimensions of these cartridges ensured that they could not chamber in older black powder rifles of similar calibre – a very important safety consideration.
Amongst the lesser-known cartridges developed by Jeffery are oddities such as the .333/ .280 and .303 Rimless Magnum, which never made it commercially. If you had to rank Jeffery’s cartridges according to popularity, the .404 and .500 would be right at the top and the .333/ .280 at the bottom. Somewhere in between lies the .333 Jeffery – not quite as popular as the .404 and .500 (for which new hunting rifles are still being built today), but not quite as unknown as the .333/.280.
For many years, Jeffery’s clients had requested him to develop a cartridge similar to the .256 Mannlicher but using a heavier bullet for use against larger game. The .256 Mannlicher had been a great success for Jeffery, and he had been selling the “Jeffery Mannlicher Sporting Rifle” since 1895. Initially, he used the 1895 Mannlicher action and the rimmed 6.5x53mmR cartridge, changing to the Mannlicher-Schönauer action and the rimless
