Two major developments at the turn of the 20th century set the course for the development of .416 Rigby as a successful big game hunting cartridge. The first was the development of
cordite in the UK in 1889 and second the development of the Magnum Mauser 98 action based on the
Gewehr 98 bolt-action magazine rifle which was designed in Germany. Prior to the invention of cordite, rifles used
black powder as a propellant. The combustion of black powder produces about 55% solid products, whereas
smokeless powder such as cordite produces almost entirely gaseous combustion products. As a result, half the mass of cordite will produce roughly the same amount of propellant gases, compared to the older black powder. This means cartridges using cordite can be made smaller, or they can produce a higher pressure at the same cartridge size. The development of smokeless powder revolutionised the rifle. One version of this smokeless powder, cordite, allowed higher pressures to be developed, thereby increasing the velocity and performance of rifle cartridges. The higher velocities produced by cordite allowed the use of smaller diameter projectiles which penetrated big game much more reliably. The large bolt face and the length of the Magnum Mauser 98 No. 5 action was easily adapted for use with the .416 Rigby cartridge. As the Magnum Mauser 98 action became scarcer after World War II, .416 Rigby rifles were built on Enfield P-17 and the BRNO actions. Both the Enfield P-17 and the BRNO actions are in turn based on the Magnum Mauser 98 rifle. After World War II, with the dwindling of areas to hunt dangerous game animals, interest in the .416 Rigby cartridge and most big-bore Nitro Express cartridges began to wane. By the 1970s, with the demise of the British ammunition supplier Kynoch as an entity, the supply of .416 Rigby ammunition was dwindling, and many hunters, including Selby, set aside their .416 Rigby rifles, taking up the more popular
.375 H&H Magnum,
.458 Winchester Magnum, and
.458 Lott. Between 1912 and the beginning of World War II, John Rigby & Co. produced 169 .416 Rigby rifles and 180 between 1939 and 1984. Between 1984, when Paul Roberts took over the John Rigby & Co., and 1997, when the company was purchased by Geoff Miller's investment group, 184 more rifles were produced. It was not until Bill Ruger of Sturm, Ruger & Co. began offering the Ruger Model 77 RSM Magnum Mk II in 1991 that the cartridge finally took off. Ruger produced approximately 1,000 rifles between 1991 and 2001, dramatically boosting the number of .416 Rigby rifles in circulation. With renewed interest in dangerous-game hunting in Africa, the demand for big-game cartridges increased. Major ammunition manufacturers like Norma, Federal, and Hornady began producing .416 Rigby ammunition to meet the new demand. The Kynoch brand name was licensed by Eley to Kynamco, a British ammunition manufacturer, based in Suffolk, England, which continues to manufacture .416 Rigby ammunition under the Kynoch brand name. ==Design and specifications==