.260 Remington

The .260 Remington (also known as 6.5-08 A-Square) cartridge was introduced by Remington in 1997. Many wildcat cartridges based on the .308 Winchester case had existed for years before Remington standardized this round. Although loaded to higher pressures, the ballistics of this cartridge are basically similar to the 6.5 × 55 Swedish Mauser when bullet weights do not exceed 140 grains. When loaded with heavier bullets, the 6.5x55 Swedish is capable of greater velocity. However, due to its shorter overall length, the .260 Remington has a slight advantage over the Swedish Mauser in that it can be chambered in a shorter length bolt action.

Because 6.5 mm (.264") bullets are known for their relatively high ballistic coefficients, the .260 Remington has seen success in rifle competition. It is capable of duplicating the trajectory of the .300 Winchester Magnum while generating significantly lower recoil. Also, converting a rifle chambered for the .308 Winchester (or any of its offspring, such as the .243 Winchester, 7mm-08 Remington or .338 Federal) to .260 Remington generally requires little more than a simple barrel change.

The .260 Remington is a Delta L problem cartridge, meaning it can present unexpected chambering and/or feeding problems. The Delta L problem article explains this problem in more detail.

Controversy
The cartridge that is now popularly known as the .260 Remington was submitted for standardization under SAAMI by the A-Square Company in 1996, several months prior to Remington announcing their plans to introduce the cartridge under their own name. A-Square's submission was called the 6.5-08 A-Square. Some users continue to refer to the cartridge under this name.