.264 Warrior Magnum

The .264 Warrior Magnum (also known as 6.5x40mm) is a 6.5 mm caliber intermediate cartridge that was developed specifically for long-range Benchrest shooting and hunting in AR-15 platform because it has a flatter trajectory and retains greater terminal energy at extended ranges than other AR-15 cartridges due to its higher ballistic coefficient. In Canada and the United States, it is used for taking deer and other medium-sized game.

Development and history
The cartridge was designed by Hector Rojas as a low recoil, high accuracy, long-range cartridge for the AR-15 platform in 1971. He was a big advocate of the 6.5 caliber for its streamlined, high ballistic coefficient or (BC) bullet that give up little of their in-flight velocity and a huge fan of the AR-15/M16 rifle, which he came to love while in the service. However, he found that the 5.56 NATO cartridge was inadequate for his needs. He sought to develop a new round for the AR-15 rifle to improve performance and accuracy.

Cartridge use
Over 30 years later in 1997, Warrior Arms came upon this old wildcat and with research and development was able to create better loads, data and combinations of bullet powder and primer in a more tuned rifle that will operate in adverse conditions. The case head diameter and negligible taper of the .264 Warrior Magnum is the same as the 5.56x45mm NATO. This means the same storage capacity of standard size M16/AR15 magazines/STANAG. Any firearm with a 5.56 NATO bolt face can be converted to .264 Warrior Magnum by re-barreling the action, making the 264 warrior magnum well in AR-15 based rifles.