John Rigby had further plans for his .416 cartridge case. When World War I began in June 1914, he was working with Kynoch to develop the Rigby .322 Nitro cartridge. They intended to use a .330 diameter bullet weighing 250 grains. The velocity should have been about 3,000 feet per second, which would have produced more than 5,000 foot pounds of energy at the muzzle. Completion of the project was delayed until after the war, but with John Rigby’s death in 1916 all development ceased.
In the 1950s, American arms designer Roy Weatherby added a belt to the .416 Rigby cartridge case for a number of his proprietary rounds. In the early 1980s, an American company called Research Armament, working with the Finnish ammunition maker Lapua, developed the .338 Lapua Magnum. Using the 416 Rigby case and a 250 grain .338 diameter bullet – it was almost identical to what John Rigby had conceived seven decades earlier. The .338 is generally considered the ‘ultimate’ for long range sniper needs.