The .404 Jeffery is a large-caliber, rimless cartridge designed for large, dangerous game, such as the “Big Five” (elephant, rhino, cape buffalo, lion and leopard) of Africa. Other names for this cartridge include .404 Jeffery Rimless, .404 Rimless Nitro Express, and 10.75× 73mm. It was created by W.J. Jeffery & Co of England based on their desire to duplicate performance of the .450/400 (3¼”) cartridge.
There are two basically similar sets of dimensions for this case, depending on the manufacturer. The .404 Jeffery as originally loaded fired a .423″ diameter bullet of either 300 gr (19 g) with a muzzle velocity of 2,600 ft/s (790 m/s) and muzzle energy of 4,500 foot-pounds force (6,100 N·m) or 400 gr (26 g) with a muzzle velocity of 2,125 ft/s (648 m/s) and 4,020 foot-pounds force (5,450 N·m) of energy. It is very effective on large game and is favored by many hunters of dangerous game. Performance and recoil are similar to other African dangerous game cartridges. The .404 Jeffery was popular with hunters and game wardens in Africa because it gave good performance with a manageable level of recoil. By way of comparison, the .416 Rigby and .416 Remington Magnum both fire a 400 grain .416 in bullet at 2,400 feet per second (730 m/s) with a muzzle energy of approximately 5,000 foot-pounds force (6,800 N·m), which handily exceeds the ballistic performance of the .404 Jeffery but at the price of greater recoil.