Roy Weatherby built the company that bears his name on the premise that speed trumps weight when it comes to harvesting game quickly and humanely. Weatherby Magnum cartridges have invariably started as wildcat loads designed to outpace the competition in the most popular hunting calibers. The 6.5-300 Weatherby Magnum is no different, a .300 Wby. Mag. case necked down for a 0.264” bullet, it enters the field as the world’s fastest 6.5 mm production load.