.222 Remington Magnum was created by lengthening the case and shortening the neck of the highly accurate and very popular .222 Remington cartridge, which dominated varmint and benchrest shooting during the 1950s. Case capacity is about 20% greater than that of the .222 Remington, producing moderately higher muzzle velocities. The .222 Remington Magnum served as the basis for the German-developed 5.6×50mm Magnum sporting cartridge.

The .222 Remington Magnum was a short-lived commercially produced cartridge derived from the .222 Remington