.338 Xtreme

Introduced in 2008 the .338 Xtreme cartridge (or .338 XT for short), is based on a necked down .505 Gibbs cartridge case with a sharper 35 degree shoulder angle. The cases, commercially produced by Bertram Bullets, have a length of 3.030" and a head diameter of 0.640". Case capacity is 167.5 grains. Factory loads drive a 266 grain bullet at 3350 feet per second from a 30" barrel. The factory loads are loaded with a tellurium copper alloy solid very-low-drag bullet, These projectiles are manufactured by Xtreme Machining and of a patent pending design. The secant ogive projectile measures 1.808" long, including a 6 degree boat tail of 0.285". The patent refers to a "dual diameter" aspect of the projectile, where the main cylindrical portion of the bullet measures 0.331", 0.001" greater than the lands of the rifling. About 1.440" from the tip, the diameter increases to 0.338", creating a 0.15" "driving band". This both reduces driving force required for the high muzzle velocity as well as improves accuracy.