The .338-378 Weatherby Magnum is a high-velocity, long-range hunting cartridge developed by Weatherby in 1998. It is based on the .378 Weatherby Magnum case necked down to accept .338 caliber bullets. Known for its impressive ballistic performance, the .338-378 Weatherby Magnum is capable of delivering high energy and velocity, making it suitable for taking down large game such as elk, moose, and even bear at extended ranges.
The cartridge offers flat trajectories and significant stopping power, with muzzle velocities typically exceeding 3,000 feet per second when firing 200 to 300-grain bullets. This makes it highly effective for long-distance shooting scenarios. However, the .338-378 Weatherby Magnum also produces substantial recoil, which can be a consideration for shooters sensitive to heavy kickback.
It is most commonly used by hunters and long-range shooting enthusiasts who require superior ballistic performance. Because of its high power and specialized nature, it is less common than other .338 caliber cartridges and often requires a rifle specifically chambered for it.