|Place of origin||England|
|Designer||Jeffery of England|
|Variants||.404 Rimless Nitro Express, 10.75 × 73 mm|
|Case type||Rimless, bottleneck|
|Bullet diameter||.423 in (10.7 mm)|
|Neck diameter||.452 in (11.5 mm)|
|Shoulder diameter||.530 in (13.5 mm)|
|Base diameter||.545 in (13.8 mm)|
|Rim diameter||.543 in (13.8 mm)|
|Rim thickness||.05 in (1.3 mm)|
|Case length||2.875 in (73.0 mm)|
|Primer type||Large rifle magnum|
|Source(s): Norma Reloading Manual, Edition No. 1|
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 × 73 mm. It was created by Jeffery 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 " 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 and in the case of the .416 Rigby, rifles that are significantly more expensive.
Originally the .404 Jeffery was very popular with hunters in Africa and saw significant use in both British and German colonies. As the British Empire began to shrink, many of the popular British big-bore cartridges also dwindled in popularity, and the .404 Jeffery was one of them. By the 1960s it had all but disappeared from common firearm usage. This condition was mostly the result of the closing of the British Ammunition giant Kynoch, which was the primary manufacturer of the .404 Jeffery and many other British cartridges. The introduction of the .458 Winchester Magnum in 1956 in the Winchester Model 70 bolt action rifle provided an affordable alternative to the big Nitro Express rifles and cartridges and helped to hasten the demise of the .404 Jeffery. Winchester also started a marketing campaign at about this time called "Winchester in Africa" with much success. Renewed interest in heavy game rifles and political stability in Africa has led to a resurgence in African hunting and the rifles suited for it. Kynoch Ammunition has reopened as Kynamco Limited Kynoch Ammunition. Hornady and Norma of Sweden are also offering .404 Jeffery ammunition.
Commercial and wildcat children
In recent times, the .404 case has seen a resurgence in use by wildcatters. This case has no belt, unlike many other magnum cartridges, which can be desirable for handloading because of possible problems with case head separation with repeated reloading of belted magnum cartridges. The rimless design also contributes to smooth feeding from the box magazine of bolt action rifles.
Some common commercial children of the .404 Jeffery case are the Remington Ultra Magnum (RUM) cartridge family, as well as the Winchester Short Magnum (WSM) cartridge family, which in turned spawned the Remington Short Action Ultra Magnum (RSAUM) cartridges and the Winchester Super Short Magnum (WSSM) families. Both the Winchester and Remington cartridges have also spawned many current wildcats.
- Axelsson, Kenneth; Holmquist, Stewe; Larsson, Christer; Nordstrom, Johan (2004). Norma Reloading Manual Edition No.1. Set Communication AB. pg. 401
- Big Bore Rifles and Cartridges (1991). Wolfe Publishing Co.:Prescott, Arizona. pg. 235 ISBN 1-879356-00-7
- The .404 Jeffery by Chuck Hawks
- Howell, Ken (1995). Designing and Forming Custom Cartridges. Precision Shooting. pp. 330, 331. ISBN 0-9643623-0-9.
- Taylor, John (Reprint edition 1977). African Rifles and Cartridges. The Gun Room Press:Highland Park, New Jersey. pg. 107 ISBN 0-88227-013-3
- The .404 Jeffery by Chuck Hawks (subscription required)
- Barnes, Frank, Cartridges of the World 4th Edition, p. 329