The .378 Weatherby Magnum was designed by

Roy Weatherby Roy Edward Weatherby (4 September 1910 – 4 April 1988), was the founder and owner of Weatherby, Inc., an American rifle, shotgun and cartridge manufacturing company founded 1945. Weatherby created an entire line of custom cartridges, and was ...

in 1953. Although inspired by the .416 Rigby, it is an original

belted magnum The term belted magnum or belted case refers to any cartridge, but generally a rifle cartridge, with a shell casing that has a pronounced "belt" around its base that continues past the extractor groove. This design originated with the British ...

design with no parent case.Any Shot You Want, The A-Square Handloading Manual, pp. 479,480 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 Federal Premium Ammunition is a wholly-owned subsidiary of the Czechoslovak Group, located in Anoka, Minnesota. With a workforce of nearly 1,500, Federal manufactures shotshell, centerfire, and rimfire ammunition and components. History The ...

to introduce the 215 Magnum primer specifically for this round. 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 conducted in African hunting grounds. Based on his safari experiences, he believed it to be desirable to improve the performance afforded by his preexisting .375 Weatherby Magnum by devising a larger cartridge more in keeping with the design philosophy of his small-bore cartridges, such as his .300 and .257 Magnums.Sierra Bullets Reloading Manual, Rifle, Second Edition, pg.287 To promote the .378, Roy Weatherby killed an

African elephant African elephants are members of the genus ''Loxodonta'' comprising two living elephant species, the African bush elephant (''L. africana'') and the smaller African forest elephant (''L. cyclotis''). Both are social herbivores with grey skin. ...

with one shot at extended range. In order to gain access to markets across the African continent by accommodating the 10.16 mm (.40 caliber) minimum bullet size required for use on dangerous game in some countries, Weatherby soon necked the .378 to 11.63 mm (.458 caliber) and introduced the resultant cartridge as the .460 Weatherby Magnum in 1957. Considered a

safari A safari (; originally ) is an overland journey to observe wildlife, wild animals, especially in East Africa. The so-called big five game, "Big Five" game animals of Africa – lion, African leopard, leopard, rhinoceros, African elephant, elep ...

-grade cartridge, the .378 Weatherby Magnum is appropriate for taking all African game animals, including the African antelopes,

Nile crocodile The Nile crocodile (''Crocodylus niloticus'') is a large crocodilian native to freshwater habitats in Africa, where it is present in 26 countries. It is widely distributed in sub-Saharan Africa, occurring mostly in the eastern, southern, and ce ...

hippopotamus The hippopotamus (''Hippopotamus amphibius;'' ; : hippopotamuses), often shortened to hippo (: hippos), further qualified as the common hippopotamus, Nile hippopotamus and river hippopotamus, is a large semiaquatic mammal native to sub-Sahar ...

, and the Big Five. Some hunters on the North American continent employ the .378 for American

elk The elk (: ''elk'' or ''elks''; ''Cervus canadensis'') or wapiti, is the second largest species within the deer family, Cervidae, and one of the largest terrestrial mammals in its native range of North America and Central and East Asia. ...

brown bear The brown bear (''Ursus arctos'') is a large bear native to Eurasia and North America. Of the land carnivorans, it is rivaled in size only by its closest relative, the polar bear, which is much less variable in size and slightly bigger on av ...

, and

polar bear The polar bear (''Ursus maritimus'') is a large bear native to the Arctic and nearby areas. It is closely related to the brown bear, and the two species can Hybrid (biology), interbreed. The polar bear is the largest extant species of 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 Free recoil / Frecoil is a vernacular term or jargon for recoil energy of a firearm not supported from behind. Free recoil denotes the translational kinetic energy (''Et'') imparted to the shooter of a small arm when discharged and is expressed i ...

with full-power loads, for an average of 72

ft·lbf The foot-pound force (symbol: ft⋅lbf, ft⋅lbf, or ft⋅lb ) is a unit of Mechanical work, work or energy in the English Engineering Units, engineering and Foot–pound–second_system#force, gravitational systems in United States customary ...

from a 9 lb rifle. This compares to 23 ft·lbf from a rifle chambered for

.30-06 Springfield The .30-06 Springfield cartridge (pronounced "thirty- aught-six" ), 7.62×63mm in metric notation, and called the .30 Gov't '06 by Winchester, was introduced to the United States Army in 1906 and later standardized; it remained in military us ...

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. 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 cartridge A wildcat cartridge, often shortened to wildcat, is a custom-made cartridge (weaponry), cartridge for which ammunition and/or firearms are not mass-produced. These cartridges are often created as experimental variants to optimize a certain ballis ...

s. It has been necked-down as the .22 Eargesplitten Loudenboomer and necked-up as the .475 A&M and .500 A-Square, and shortened to produce the .30-378 Arch (7.62mm), .338-378 KT, and .460 Short A-Square (11.63mm). Some .378-based derivatives have gone on to be part of the Weatherby line: namely, the .30-378, .338-378, .416 and .460.

Footnotes

{{DEFAULTSORT:378 Weatherby Magnum Pistol and rifle cartridges Magnum rifle cartridges Weatherby Magnum rifle cartridges

See also

Footnotes