The .300 Magnum was not the first cartridge developed by Roy Weatherby but it has been with us since 1944 and it is the most popular cartridge in the Weatherby line. In the beginning, all Weatherby cartridges were strictly for handloaders since no factory ammunition was available. During the late 1940's Weatherby started loading ammunition at his California facility, and in 1958 Normabegan to load all Weatherby ammunition. In addition to the Weatherby rifles, the Remington Model 700, Winchester Model 70, Ruger No. 1 and various rifles of foreign origin are available in .300 Weatherby Magnum. The .300 Weatherby Magnum is an excellent cartridge and considered by many experienced hunters to be ideal for shooting elk moose and lager African antelope at long range. For plains and mountain hunting of deer size game, few cartridges shoot flatter than this .300 Magnum. Due to its extremely high velocity, one only has to shoot a few deer and pronghorn with the .300 Weatherby to see that a 180 grain bullet shoots about as flat and destroys less meat than the 150 grain bullet. It is difficult to imagine better elk and moose medicine than the .300 Weatherby Magnum loaded with a Nosler or Speer200 grain bullets at 3000 fps. 

This text is based on information from “Cartridges of the World”, Hodgdon reloading manual, the cartridge designer and/or own resources.