The .270 Winchester is a rifle cartridge developed by Winchester Repeating Arms Company in 1923, and it was unveiled in 1925 as a chambering for their bolt-action Model 54[3] to become arguably the flattest shooting cartridge of its day, only competing with the .300 Holland & Holland Magnum, also introduced in the same year.

The .270 Winchester, conceived solely as a big game hunting cartridge, became very popular, in part, due to the widespread praises of gun writer Jack O'Connor who used the cartridge for 40 years and touted its merits in the pages of Outdoor Life[6][7] as well as other renowned gun writers of the time such as late Col. Townsend Whelen.

For decades the only other commercial 6.8mm cartridge available for sporting purposes was the .270 Weatherby Magnum, which offered a flatter trajectory based on the larger powder capacity allowed by the belted magnum case, however due to the higher price and offer limit, it never reached the popularity of the .270 Winchester.

Nowadays a new breed of .277" caliber cartridges have been introduced to the market, including the .270 Winchester Short Magnum, which launches a bullet of the same weight 200 fps faster from a short action mechanism; the 27 Nosler, which is even faster but requires a long magnum action, and the recent 6.8 Western, which is basically a modification of the 270 WSM firing a heavier and larger bullet with a higher ballistic coefficient.

The latest .277 round is Sig Sauer's .277 Fury, which utilizes a hybrid steel and brass case to safely reach 80,000 psi.

Additionally, the cartridge, loaded with the 130-grain bullet, retains around 1,500 foot-pounds of energy up to 400 yards, meeting the minimum recommended for hunting elk.