The .257 Weatherby Magnum is a high-velocity, flat-shooting rifle cartridge developed by Roy Weatherby in 1944. It is based on the .375 H&H Magnum case, necked down to accept a .257 caliber (6.35mm) bullet. This cartridge is known for its exceptional speed; factory loads can drive a 100-grain bullet at around 3,600 feet per second (fps), resulting in a very flat trajectory.
The .257 Weatherby Magnum is primarily used for long-range hunting of medium-sized game such as deer, antelope, and sheep. Its high velocity and flat trajectory make it well-suited for shots at varying distances, reducing the need for precise range estimation. It also has enough kinetic energy to make clean kills on these types of game.
However, its high velocity can lead to increased barrel wear compared to lower velocity rounds. Despite this, it remains popular among hunters and shooting enthusiasts who prioritize its long-range performance and terminal ballistics.