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