Winchester developed the 300 Winchester Magnum center fire rifle cartridge based totally on their 338 Winchester Magnum cartridge. This was done by shifting the cartridge’s shoulder area forward by .156” thereby elongating the case .120” and narrowing it down to admit .308” diameter bullets. It was in the year 1963 that Winchester first introduced the new 300 Winchester Magnum cartridge to the people. It was chambered in their 70 bolt action rifle model that had a 1 in 10” rifling twist. Ever since its inception, the 300 Winchester Magnum cartridges have gained popularity among long range rifle shooters and hunters and have been utilized to win quite a few 1,000 yard matches in shooting competitions. It was soon discovered by hunters also that the rifle has enough power to tackle all kinds of animals in North America. It was in the 1980’s that the story of the 300WM’s use for military sniping purposes and the US Navy began. The Navy had been on the lookout for different ki...