The .26 Nosler (6.5×66mmRB) is a rebated-rim centerfire rifle cartridge designed by Nosler and first announced in November 2013. It is the first cartridge designed by Nosler.
The name .26 Nosler refers to the first two digits in the caliber (0.264 in; 6.7 mm) of the bullets that the cartridge fires and the name of the company which created it.
The .26 Nosler is designed as a modern 6.5mm cartridge, using recent advances in firearm technology to attain exceptionally high muzzle velocities, up to 1,040 m/s (3,400 ft/s), and maintain an extremely flat trajectory. The overall cartridge length of 84.8 mm (3.340 in) is the same as that of the .30-06 Springfield, allowing the use of widely available standard-length actions.
Four of Nosler's Cartridges, the .26 Nosler, .28 Nosler, .30 Nosler, and .33 Nosler, are based on the same .300 Remington Ultra Magnum parent case. While the .26 Nosler and the .28 Nosler share the same cartridge case dimensions, the .30 Nosler has a slightly shorter length to the shoulder dimension than the .26 Nosler and the .28 Nosler, and the .33 Nosler has a shorter shoulder length dimension than that of the .30 Nosler.
When released, the .26 Nosler was claimed to be the most powerful commercial 6.5 mm cartridge in the world. The .26 Nosler, when loaded with 8.4 g (129 gr) AccuBond Long Range very-low-drag bullets, retains as much velocity at 370 m (400 yd) as the .260 Remington produces at the muzzle