The .270 Winchester is a rifle cartridge developed by Winchester Repeating Arms Company in 1923 and unveiled in 1925 as a chambering for their bolt-action Model 54 to become arguably the flattest shooting cartridge of its day, only competing with the .300 Holland & Holland Magnum, also introduced in the same year. As the .280 Remington, and the .30-06 Springfield, the .270 Winchester derived from the .30-03 parent case and the bore diameter was likely inspired by 7mm Mauser. The .270 Winchester uses a .270 inch (6.86 mm) bore diameter and a .277 inch (7.04 mm) bullet diameter. History Introduced in 1925 along with the Winchester Model 54 bolt action rifle under the name "270 WCF" (270 Winchester Centerfire), the .270 Winchester was not an immediate success due to the popularity of the relatively recently introduced .30-06 Springfield, chambered for the M1903 Springfield bolt action rifle, which was commonly "sporterized" for hunting purposes. However, the .270 Winchester attained great popularity among hunters and sporting rifle enthusiasts in the succeeding decades and especially in the post-World War II period, ranking it among the most popular and widely used big game hunting cartridges worldwide, especially with the widespread popularity of rifle scopes. Shooters started noticing that the .277" caliber cartridge was capable of shooting flatter than the popular 30–06. 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 as well as other renowned gun writers of the time such as late Col. Townsend Whelen. The cartridge was initially commercially loaded to drive a 130 grain (8.4 gram) bullet at approximately , later reduced to , demonstrating a high performance at the time of its introduction while being marketed as a suitable cartridge for big game shooting in the range. Two additional bullet weights were soon introduced: a 100-grain (6.5 gram) hollow-point bullet for varmint shooting, and a 150 grain (9.7 gram) bullet, offering a higher sectional density, which made it suitable for achieving better penetration for large sized deer, such as wapiti, and moose. However, the 130 grain bullet remains the most popular option. 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