.30-378 Weatherby Magnum

The .30-378 Weatherby Magnum is a cartridge introduced by Weatherby in 1996 that uses the same case as the previously existing .378 Weatherby Magnum and .460 Weatherby Magnum, necked down to a 30 caliber (.308 in) bullet. It is offered with bullets between 165 and 200 grains (10.7 g and 13.0 g) in factory loading, generating velocities able to exceed 3500 ft/s and muzzle energies over 4750 ftlbf. The cartridge was originally designed for hunting game at very long distances, and for marksmanship competition in excess of 1000 yd.

Performance
The .30-378 case holds as much as 120 gr of powder without requiring a compressed load. This allows the cartridge to develop more energy than the .300 Remington Ultra Magnum, .300 Winchester Magnum and .375 H&H Magnum, especially when handloads are used. The .30-378 has comparable muzzle energy to the larger .338 Lapua in military use. When bullets heavier than 200 gr are loaded, the .30-378 can exceed the .458 Winchester Magnum in terms of both Muzzle Energy and Taylor Knockout Value.

Note: Using the bullet weight and muzzle velocity in each cartridge that provided the maximum muzzle energy. Data for the .30-378 is from. Loading data for all other cartridges can be found at

Weatherby claims the .30-378 is currently the most powerful .30 caliber cartridge in the world, retaining more energy and velocity at one quarter mile than is possessed by a .30-06 upon leaving the barrel. However, the later claim appears not to be accurate when you compare bullets of the same weight, based on a check of available data (See chart below).

Note: data for the .30-378 from Weatherby (which tracks closely to what handloaders can achieve based on loading data at . Data from the .30-06 is also from Hodgdon. The initial data used is included here for anyone who cares to run the calculations themselves.

Costs
Rifles built by Weatherby are available in .30-378, and ammunition is significantly more expensive than other cartridges, with ammunition costing upwards of $100 USD for a box of 20 rounds as of 2007. Weatherby offers this caliber in several versions of its Mark V rifle. Due to the strong recoil a round of this energy can create, all Weatherby rifles offered in this caliber include a muzzle-brake. Sako offers the TRG-S also in .30-378 Weatherby.

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Cartridge:rifles