The .308 Winchester (pronounced: "three-oh-eight" or "three-aught-eight") is a rimless, bottlenecked rifle cartridge and is the commercial cartridge from which the 7.62×51mm NATO round was derived. The .308 Winchester was introduced in 1952, two years prior to the NATO adoption of the 7.62×51mm NATO T65. Winchester branded the cartridge and introduced it to the commercial hunting market as the .308 Winchester. Winchester's Model 70 and Model 88 rifles were subsequently chambered for the new cartridge. Since then, the .308 Winchester has become the most popular short-action, big-game hunting cartridge worldwide. It is also commonly used for civilian target shooting, military sniping, and police sharpshooting. The relatively short case makes the .308 Winchester especially well-adapted for short-action rifles. When loaded with a bullet that expands, tumbles, or fragments in tissue, this cartridge is capable of high terminal performance.
Although very similar to the military 7.62×51mm NATO specifications, the .308 cartridge is not identical, and there are special considerations that may apply when mixing these cartridges with 7.62×51mm NATO, and .308 Winchester chambered arms. Their interchange is, however, considered safe by the Sporting Arms and Ammunition Manufacturers Institute (SAAMI).
The .308 Winchester has 3.64 ml (56.0 grains) cartridge case capacity. The exterior shape of the case was designed to promote reliable case feeding and extraction in bolt action rifles and machine guns alike, under extreme conditions.
.308 Winchester maximum C.I.P. cartridge dimensions. All dimensions in millimeters (mm) and inches.
Americans would define the shoulder angle at alpha/2 = 20 degrees. The common rifling twist rate for this cartridge is 305 mm (1 in 12 in), 4 grooves, Ø lands = 7.62 mm, Ø grooves = 7.82 mm, land width = 4.47 mm and the primer type is large rifle.
According to the official C.I.P. (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives) rulings the .308 Winchester can handle up to 415.00 MPa (60,191 psi) Pmax piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers. This means that .308 Winchester chambered arms in C.I.P. regulated countries are currently (2008) proof tested at 519.00 MPa (75,275 psi) PE piezo pressure.
North American SAAMI maximum pressure for the 308 Winchester is 62,000 PSI.
The .308 Winchester is one of the most popular hunting cartridges in the United States, and possibly the world. It has gained popularity in many countries as an exceptional cartridge for game in the medium- to large-sized class. In North America it is used extensively on whitetail deer, pronghorn and even the occasional caribou or black bear.
Clay Harvey, an American gun writer, says it is usable on moose and elk. Layne Simpson, an American who has hunted in Sweden, says he is surprised how many hunters there use the cartridge. Craig Boddington was told by a Norma Precision executive that the .308 is one of Norma's best-selling calibers.
In Africa the .308 Win is one of the most popular calibers among Bushveld hunters and is used on anything from duiker right up to the massive eland (a small and large African antelope respectively). Proponents of the hydrostatic shock theory contend that the .308 Winchester has sufficient energy to impart hydrostatic shock to living targets when rapidly expanding bullets deliver a high rate of energy transfer.
The .308 Winchester has slightly more drop at long range than the .30-06 Springfield, owing to its slightly lower (100 ft/s) muzzle velocity with most bullet weights. Cartridges with significantly higher muzzle velocities, such as the .300 Winchester Magnum can have significantly less drop at long range.
Several more cartridges have been developed using the .308 Winchester as a parent case, some becoming very popular for hunting, particularly in North America. These are the .243 Winchester, the .260 Remington (a.k.a. 6.5-08 A-Square), the 7 mm-08 Remington, the .338 Federal, and the .358 Winchester (a.k.a. 8.8×51mm). In 1980, two rimmed cartridges based on the .308 Winchester were introduced for use in the Winchester Model 94 XTR Angle Eject rifle: the .307 Winchester and the .356 Winchester..243 Winchester