The .308 Winchester is a smokeless powder rimless bottlenecked rifle cartridge widely used for hunting, target shooting, police, military, and personal protection applications globally. It is similar but not identical to the 7.62×51mm NATO cartridge. History During the 1940s, the .300 Savage became the basis for experiments on behalf of the U.S. military that resulted in the development of the T65 series of experimental cartridges. The original experimental case design by the Frankford Arsenal was designated the T65 and was similar to the .300 Savage case, but with less taper. The experimental cases were made from standard .30-06 Springfield cases which gave a little less capacity than standard .300 Savage cases because the Frankford Arsenal cases had slightly thicker case walls. The later T65 iterations were lengthened compared to the original T65 case and provided a ballistic performance roughly equal to the U.S. military .30-06 Springfield service cartridge. Over forty years of technical progress in the field of propellants allowed for similar service cartridge performance from a significantly shorter, smaller case with less case capacity. Winchester saw a market for a civilian model of the late T65 series designs and introduced it in 1952, two years prior to the NATO adoption of the T65E5 experimental cartridge iteration under the 7.62×51mm NATO designation in 1954. Winchester branded the cartridge and introduced it to the commercial hunting market as the .308 Winchester. Winchester's Model 70, Model 88 and Model 100 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 hunting, target shooting, metallic silhouette, bench rest target shooting, Palma shooting, metal matches, 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. Cartridge dimensions 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 =