The .300 Winchester Magnum (also known as .300 Win Mag Ammo or 300WM) (7.62×67mmB, 7.62x66BR) is a belted, bottlenecked magnum rifle cartridge that was introduced by 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 Ammo is extremely versatile and has been adopted by a wide range of users including hunters. Target shooters, military units, and law enforcement departments. Hunters found the cartridge to be an effective all-around choice with bullet options ranging. From the flatter shooting 165 grain to the harder hitting 200+ grain selections available from the factory. The .300 Win Mag Ammoremains the most popular .30 caliber magnum with American hunters. Despite being surpassed in performance by the more powerful .300 and .30-378 Weatherby Magnums and the newer .300 Remington Ultra Magnum.
It is a popular selection for hunting moose, elk, and bighorn sheep. It can deliver better long range performance with better bullet weight than most other .30 caliber cartridges. Military and law enforcement departments adopted the cartridge for long range sniping and marksmanship. As a testament to its accuracy, since its introduction it has gone on to win several 1,000-yard (910 m) competitions. 300 Win Mag Ammo
Prior to the design of the .300 Winchester Magnum there were several cartridges that provided what could be best described as a magnum level of energy. The heritage of .30 caliber (7.62 mm) magnums can be traced back to the .30 Newton in 1913 and to the .300 H&H Magnum in 1925. The .300 H&H Magnum was too long for the Mauser and Springfield standard length rifle actions and required specialized rifles with a Magnum size action.