.300 Winchester Magnum
| .300 Winchester Magnum | ||||||||||||||||||||||||
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.300 Winchester Magnum (center) flanked by its parent cartridges: the .338 Winchester Magnum (left) and the .375 H&H Magnum (right). | ||||||||||||||||||||||||
| Type | Rifle, Large game | |||||||||||||||||||||||
| Place of origin | United States | |||||||||||||||||||||||
| Production history | ||||||||||||||||||||||||
| Designer | Winchester Repeating Arms Company | |||||||||||||||||||||||
| Designed | 1963 | |||||||||||||||||||||||
| Specifications | ||||||||||||||||||||||||
| Parent case | .375 H&H Magnum | |||||||||||||||||||||||
| Case type | Belted, bottleneck | |||||||||||||||||||||||
| Bullet diameter | .308 in (7.8 mm) | |||||||||||||||||||||||
| Land diameter | .300 in (7.6 mm) | |||||||||||||||||||||||
| Neck diameter | .339 in (8.6 mm) | |||||||||||||||||||||||
| Shoulder diameter | .489 in (12.4 mm) | |||||||||||||||||||||||
| Base diameter | .513 in (13.0 mm) | |||||||||||||||||||||||
| Rim diameter | .532 in (13.5 mm) | |||||||||||||||||||||||
| Rim thickness | .050 in (1.3 mm) | |||||||||||||||||||||||
| Case length | 2.62 in (67 mm) | |||||||||||||||||||||||
| Overall length | 3.34 in (85 mm) | |||||||||||||||||||||||
| Case capacity | 94 gr H2O (6.1 cm3) | |||||||||||||||||||||||
| Rifling twist | 1 in 10 in (250 mm) | |||||||||||||||||||||||
| Primer type | Large Rifle Magnum | |||||||||||||||||||||||
| Maximum pressure (C.I.P.) | 62,366 psi (430.00 MPa) | |||||||||||||||||||||||
| Maximum pressure (SAAMI) | 64,000 psi (440 MPa) | |||||||||||||||||||||||
| Maximum CUP | 54,000 CUP | |||||||||||||||||||||||
| Ballistic performance | ||||||||||||||||||||||||
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| Test barrel length: 24 inches (61 cm) Source: Accurate Powders load guide v3.5 Hodgdon powders achieve approx 100fps less. | ||||||||||||||||||||||||
The .300 Winchester Magnum (also known as .300 Win Mag or .300 WM) (7.62×67mmB, 7.62×66BR) is a belted, bottlenecked magnum rifle cartridge that was introduced by the Winchester Repeating Arms Company in 1963. The .300 Winchester Magnum is a magnum cartridge designed to fit in a standard rifle action. It is based on the .375 H&H Magnum, which has been blown out, shortened, and necked down to accept a .30 caliber (7.62 mm) bullet.
The .300 Win Mag is extremely versatile and has been adopted by a wide range of users, including big game hunters, target shooters, military units, and law enforcement departments.
Many hunters have found the cartridge to be an effective all-around choice, with bullet options ranging from the flatter-shooting 150-grain to the harder-hitting 200+ grain selections available in factory ammunition. The .300 Win Mag remains the most popular .30-caliber magnum among American hunters, despite not being as fast as more powerful .300 Magnums such as the .300 Weatherby Magnum and .30-378 Weatherby Magnum as well as the newer .300 Remington Ultra Magnum, .300 Norma Magnum, .30 Nosler, and .300 PRC, though all of these must be chambered in a long magnum action, while the .300 Win Mag uses a standard length action, resulting in a lighter rifle.
It was designed as a hunting cartridge and is widely used all over the world for hunting a wide range of mid-to-large-sized big game such as North American moose, elk, bighorn sheep, mule deer and white-tailed deer, making it one of the most versatile big game hunting cartridges.
The .300 Win Mag is capable of delivering better long-range performance with heavier, large ballistic coefficient projectiles than any other standard and short-length .30 caliber cartridge. Military and law enforcement departments have also adopted the cartridge as a long-range sniper round, intended to be used for shots at longer ranges than the .308 Winchester. As a testament to its accuracy, following its introduction, it went on to win several 1,000-yard (910 m) competitions.