.378 Weatherby Magnum | ||||||||||||||||||||||||
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Type | Rifle | |||||||||||||||||||||||
Place of origin | South Gate, California | |||||||||||||||||||||||
Production history | ||||||||||||||||||||||||
Designer | Roy Weatherby | |||||||||||||||||||||||
Designed | 1953 | |||||||||||||||||||||||
Manufacturer | Weatherby | |||||||||||||||||||||||
Produced | 1953-Present | |||||||||||||||||||||||
Specifications | ||||||||||||||||||||||||
Case type | Belted, bottleneck | |||||||||||||||||||||||
Bullet diameter | .375 in (9.5 mm) | |||||||||||||||||||||||
Neck diameter | .399 in (10.1 mm) | |||||||||||||||||||||||
Shoulder diameter | .560 in (14.2 mm) | |||||||||||||||||||||||
Base diameter | .582 in (14.8 mm) | |||||||||||||||||||||||
Rim diameter | .579 in (14.7 mm) | |||||||||||||||||||||||
Rim thickness | .063 in (1.6 mm) | |||||||||||||||||||||||
Case length | 2.913 in (74.0 mm) | |||||||||||||||||||||||
Overall length | 3.65 in (93 mm) | |||||||||||||||||||||||
Rifling twist | 1 in 12 in (300 mm) | |||||||||||||||||||||||
Primer type | Large rifle magnum | |||||||||||||||||||||||
Ballistic performance | ||||||||||||||||||||||||
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Test barrel length: 26 in (66 cm) Source(s): Weatherby [1] / Nosler [2] |
The .378 Weatherby Magnum was designed by Roy Weatherby in 1953.[3][4] Although inspired by the .416 Rigby, it is an original belted magnum design with no parent case.[5] The cartridge features a high powder capacity relative to its bore size, and can hold upwards of 7.13 g (120 gr) of powder. This consideration prompted the Federal Cartridge Company to introduce the 215 Magnum primer specifically for this round.[5] The .378 shares the double radius shoulder design found on the other Weatherby magnum cartridges.
The impetus for the development of the .378 arose from Roy Weatherby’s extensive field testing in African hunting grounds. Based on his experiences, he viewed it as desirable to improve the performance gains of his preexisting .375 Weatherby Magnum compared to its parent case, the .375 H&H Magnum, by devising a high velocity cartridge more similar in concept—relative to caliber—to his small bore cartridges, such as his .300 and .257 Magnums.[6][7]
To promote the .378, Roy Weatherby killed an African elephant with one shot at extended range while on safari. In order to gain access to hunters across the African continent and accommodate the 10.16 mm (.40 caliber) minimum bullet size required for use on dangerous game in some countries,[5] Weatherby soon necked the .378 to 11.63 mm (.458 caliber) and introduced the resultant cartridge as the .460 Weatherby Magnum, which he introduced in 1957.[8]
Considered a safari-grade cartridge, the .378 Weatherby Magnum is appropriate for taking all African game animals from large African antelopes, Nile crocodile, hippopotamus, to the Big Five game. Some hunters on the North American continent employ the .378 for American elk, brown bears, and polar bear. With proper bullet selection, the .378 provides a similar trajectory to and greater downrange energy than the .300 Winchester Magnum, .300 Weatherby Magnum, and .338 Lapua Magnum.
The .378 Weatherby generates considerable free recoil with full-power loads, for an average of 72 ft·lbf from a 9 lb rifle. This compares to 23 ft·lbf from a rifle chambered for .30-06 Springfield or 44 ft·lbf for the .375 H&H Magnum. However, the .458 Winchester Magnum generates 78 ft·lbf and the .458 Lott produces 86 ft·lbf of free recoil.[9] It should also be noted that Weatherby Mark V rifles chambered in this cartridge are equipped from the factory with removable muzzle brakes that greatly reduce felt recoil.
The .378 has been responsible for numerous wildcat cartridges, being necked-down as the .22 Eargesplitten Loudenboomer and necked-up as the .475 A&M and .500 A-Square.[10][11] Some of the .378 Weatherby Magnum wildcat cartridges are shortened versions, like the .30-378 Arch (7.62 mm) and the .460 Short A-Square (11.63 mm).[12][13] Some .378-based derivatives have gone on to be part of the Weatherby line: namely, the .30-378, .338-378, .416 and .460.[14]
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