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 6.5×55mm when bullet weights do not exceed 140 grains. When loaded with heavier bullets, the 6.5×55mm is capable of greater velocity.Due to its shorter overall length the .260 Remington can be chambered in a shorter length bolt actionthan the 6.5mm Swedish.
Because 6.5 mm (.264") bullets have 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.
Remington has had a track record of adopting successful wildcat cartridges into the Remington fold by offering rifles and ammunition and at times attaching their name to the cartridge. Like many cartridges such as the .22–250 Remington, .25-06 Remington and the 7 mm-08 Remington, the .260 Remington started its life as a wildcat cartridge called the 6.5-08 and was eventually released as a commercial cartridge by Remington. However, it was not Remington who first attempted to standardize the cartridge. LTC Arthur Alphin and his company A-Square LLC submitted the first proposal and drawings to SAAMI for the standardization of the cartridge. Remington was to file similar papers with SAAMI to do the same a few months later. When the dust settled it was found that the 6.5-08 would be called the .260 Remington instead of 6.5–08 A-Square.
The 6.5 -08 cartridge was created simply by necking down the .308 Winchester or the 7 mm-08 Remington or necking up the .243 Winchester cartridge to create the case. Since all these cartridges had the same basic dimensions right up to the shoulder, case forming was a relatively simple task for anyone with an understanding of reloading and case forming. As the parent cartridges were readily available for low cost, the 6.5 -08 was often an economical alternative to cartridges such as the 6.5x55 Swedish Mauser. What the 6.5-08 provided over the .243 Winchester, .308 Winchester and to a lesser degree the 7 mm-08 Remington was bullets with excellent ballistic coefficients and sectional densities relative to their weights.
Since the 6.5-08 was a wildcat cartridge, there were variations between cartridge chambers depending on the reamer used to cut the chamber. Furthermore depending on whether one chose to form the case from .243 Winchester or .308 Winchester influenced the neck thickness and therefore the dimensions of the cartridge. A cartridge formed for a specific rifle may or may not successfully chamber or worse may reach dangerous pressures in another. Standardizing the cartridge served the purpose of providing design specifications for the cartridge so as to address the issues the cartridge experienced as a wildcat cartridge.
.264 caliber (6.5 mm) caliber has historically been unsuccessful in North America but has been one of the mainstays in Europe especially in the Scandinavian countries. The 6.5x54 Mannlicher-Schoenauer, 6.5x55 Swedish Mauser, 6.5x57 Mauser 6.5-284 Norma have loyal followings in Europe. Starting with the .264 Winchester Magnum and later the 6.5 Remington Magnum North American cartridges in this caliber have been largely failures. The .260 Remington appeared to be following this North American trend, with Remington only producing the Model Seven Synthetic in the .260 Remington for 2011 as it has discontinued such rifles as the Model 700 CDL and the Model Seven (including the youth model) in the .260 Remington. However, Remington continues to manufacture several types of loaded ammunition for .260 Remington. The use of the .260 Remington by SGT Sherri Gallagher to win the 2010 NRA High Power National Championship has sparked a resurgence in the round, and Lapua announced at the 2011 SHOT show that it would be manufacturing .260 Remington brass.