6.5-300 Weatherby Magnum

In the 1940's, Roy Weatherby began developing a series of hunting cartridges that would become the famous Weatherby magnums.

- Brian Pearce

Perhaps the most popular and best known is the .300 Weatherby Magnum that is based on .300 H&H Magnum case with a double-radius shoulder. During the early 1950's, he took his .300 case and necked it down to accept 6.5mm/.264-inch bullets, but for several reasons that cartridge was not added to the Weatherby line, so it became a wildcat and has enjoyed a dedicated following.

With new powders and a wide selection of new hunting bullets, along with renewed interest in 6.5-caliber cartridges from hunters and long-range shooters, in 2015 Weatherby announced the 6.5-300 Weatherby as a standard offering. Initial factory loads included a Barnes 127-grain LRX bullet at 3,531 fps, a Swift 130-grain Scirocco at 3,476 fps and a Swift 140-grain A-Frame at 3,395 fps (recorded from a 26-inch barrel). These impressive ballistics, along with low-drag bullets, results in an unusually flat trajectory. It is the fastest commercially available, SAAMI 6.5 cartridge.

The 6.5-300 is housed in Weatherby’s flagship rifle, the Mark V, that is currently manufactured at Weatherby’s Paso Robles, California, headquarters. Production began in early 2016, and sales have been strong. All 6.5-300 Weatherby Magnum ammunition is also manufactured under the Weatherby roof, which is the first time in over 50 years that the company has manufactured ammunition. Cases are still produced by Norma of Sweden and exhibit the usual high quality. I have watched the production of ammunition, tested it in Weatherby’s shooting tunnel, on a 1,000-yard range and at home. It is carefully engineered to offer the best blend of velocity and accuracy with excellent big-game hunting bullets.

With a maximum overall cartridge length of 3.600 inches, the 6.5-300 requires the use of a .375 H&H Magnum length action. Like other Weatherby cartridges adopted by SAAMI, it has a maximum average pressure of 65,000 psi.