.338 Winchester Magnum - Cartridge History

Cartridge History

The .338 Winchester Magnum traces its heritage to the experiments conducted by Charles O’Neil, Elmer Keith and Don Hopkins with cartridges firing .333 in (8.5 mm) bullets in the late 1940s. The use of .333 in (8.5 mm) bullets may seem odd today but at the time this was the standard diameter of European .33 caliber bullets which were more common than the .338 in (8.6 mm) diameter bullets used in cartridges such as the .33 Winchester. Furthermore the .333 in (8.5 mm) were available in heavier weights than the .338 in (8.6 mm) bullets. O’Neil, Keith and Hopkins experiments lead to the creation of the .333 OKH, which was based on the .30-06 Springfield case necked up to accept .33 caliber bullets and the .334 OKH which used a shortened .375 H&H Magnum necked down to accept the same bullets.

The .338 Winchester Magnum was introduced in 1958 together with the .264 Winchester Magnum and the .458 Winchester magnum; all of which used a common case design based on the .375 H&H Magnum case blown out and shortened to 2.500 in (63.5 mm) much like the .334 OKH. When the cartridge was introduced, Winchester offered a 200 gr (13 g) at 3,000 ft/s (910 m/s), a 250 gr (16 g) at 2,700 ft/s (820 m/s) and a 300 gr (19 g) at 2,450 ft/s (750 m/s). Sometime later, Winchester introduced the Winchester Model 70 Alaskan chambered for the cartridge. This chambering left little doubt that the cartridge was intended for big heavy dangerous game.