.30-378 Weath. Mag.

The .30-378 Weatherby Magnum is a powerhouse cartridge with an interesting origin steeped in long-range shooting innovation. Developed by the legendary Roy Weatherby in 1959, the .30-378 was originally conceived as an experimental round in collaboration with the U.S. Army for high-velocity, long-range applications. Its parent case is the massive .378 Weatherby Magnum, necked down to accept .30 caliber bullets, a combination that pushed the performance limits of conventional centerfire cartridges at the time. Though it began as a benchrest and experimental cartridge, Weatherby officially introduced the .30-378 Weatherby Magnum as a commercial offering in 1996, rapidly earning a reputation for being one of the fastest and flattest-shooting .30 caliber cartridges in the world.

In terms of practical applications, the .30-378 Weatherby Magnum is renowned among reloaders and precision shooters who seek extreme performance for long-range hunting and target shooting. Due to its blistering velocities—often exceeding 3,400 feet per second with appropriate bullet weights—this caliber excels in scenarios where ultra-flat trajectories and retained energy at extended ranges are critical. Long-range hunters admire it for delivering unmatched downrange authority, making ethical shots on large game at distances previously reserved for magnum-class calibers. It’s a favorite among those pursuing challenging shots out west on open-country species, where longer engagements are the norm.

For hunting, the .30-378 Weatherby Magnum is particularly suited to large North American game such as elk, moose, and even bear due to its deep penetration, high energy, and superior ballistic performance. The cartridge also finds favor among African plains game hunters, with sufficient stopping power and bullet selection for tough animals at extended distances. Reloaders who enjoy pushing ballistic boundaries often choose this caliber for shooting steel at 1,000 yards and beyond, thanks to its resistance to wind drift and extraordinary retained velocity.

Typical bullet weights for the .30-378 Weatherby Magnum range from 150 to 200 grains, with most reloaders favoring heavy-for-caliber bullets in the 180-200 grain spectrum to maximize sectional density and energy for big game. The cartridge’s generous case capacity—over 130 grains of water—allows for a wide variety of slow-burning powders, which can be fine-tuned for optimal performance with match or hunting projectiles. The .30-378’s notoriously sharp recoil and appetite for premium components also make it a favorite of experienced reloaders who appreciate the challenge and the potential for custom-tailored ballistics. Overall, the .30-378 Weatherby Magnum is the choice for those who demand best-in-class .30-caliber magnum performance and are willing to put in the work at the reloading bench to realize its full potential.