The .338-378 Weatherby Magnum started out as the wildcat cartridge, .338-378 Keith-Thomson Magnum during the early 1960s. Keith and Thomson are

Elmer Keith Elmer Merrifield Keith (March 8, 1899 – February 12, 1984) was an American rancher, firearms enthusiast, and author. Keith was instrumental in the development of the first magnum revolver cartridge, the .357 Magnum, as well as the later .44 ...

and R.W. "Bob" Thomson. The 338-378 Keith-Thomson Magnum is a quarter of an inch shorter than the full length 338-378 Weatherby Magnum, this was because they thought it was better balanced with the slowest powder generally available at that time (H4831). The .338-378 Weatherby Magnum was added to the

Weatherby Weatherby, Inc. is an American gun manufacturer founded in 1945 by Roy Weatherby. The company is best known for its high-powered magnum cartridges, such as the .257 Weatherby Magnum, .270 Weatherby Magnum, .300 Weatherby Magnum, .340 Weat ...

product line in 1998. The .338-378 Weatherby Magnum's parent case is the .378 Weatherby Magnum. The .338-378 Weatherby Magnum is created by necking down the .378 Weatherby Magnum to 8.59 mm (.338 in) then

fire forming The term fire forming in firearms refers to the process of thermomechanically reshaping a metallic cartridge case to optimally fit a new chamber by firing it within that chamber.Glenn Newick, "The Ultimate in Rifle Accuracy", Stroger Publishing C ...

it in the rifle chamber. The .338-378 Weatherby Magnum has a case capacity of about 8.1 g (125 gr). Bullets commercially available for the .338-378 Weatherby Magnum range from: 11.7 g (180 gr) to 19.4 g (300 gr) in the construction of; boat-tail hollow-point; boat-tail pointed soft; pointed soft point; heavy jacketed pointed soft point; partition; multi-core; truncated solid and monolithic solid. The .338-378 Weatherby Magnum's main appeal is long-range shooting. A Weatherby factory cartridge loaded with a 16.2 g (250 gr) hunting bullet, in a rifle with a 71 cm (28 in) barrel will yield a muzzle velocity of 933 m/s (3060 ft/s) and muzzle energy of 7046 J (5197

ft·lbf The foot-pound force (symbol: ft⋅lbf, ft⋅lbf, or ft⋅lb ) is a unit of work or energy in the engineering Engineering is the use of scientific principles to design and build machines, structures, and other items, including brid ...

). This same bullet will carry a down range velocity to 457 m (500 yd) of 648 m/s (2125 ft/s) and energy of 3391 J (2501 ft · lb_f). A hand loaded .338-378 Weatherby Magnum used for 1000 yd target shooting loaded with a 19.4 g (300 gr) boat-tail hollow point from a rifle with a 71 cm (28 in) target barrel will yield a muzzle velocity of 917 m/s (3010 ft/s), at 914 m (1000 yd) will carry a down range velocity of 590 m/s (1936 ft/s) and at 1372 m (1500 yd) will still be carrying a

supersonic Supersonic speed is the speed of an object that exceeds the speed of sound ( Mach 1). For objects traveling in dry air of a temperature of 20 °C (68 °F) at sea level, this speed is approximately . Speeds greater than five times ...

down range velocity of 462 m/s (1517 ft/s). The .338-378 Weatherby Magnum is appropriate for hunting all game animals on the North American, European and Asian continents. In Africa the 338-378 Weatherby Magnum is appropriate for taking medium and large game. The

free recoil Free recoil 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 in joules ( ...

of the 338-378 Weatherby Magnum from a (11 lb) rifle (including magazine rounds, scope, base and rings) is 73 J (54 ft · lb_f) as compared to an average 27 J (20 ft · lb_f) 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 use ...

. The Finnish .338 Lapua Magnum (.338 LM) cartridge introduced in 1989, the American .338 Remington Ultra Magnum (.338 RUM) cartridge introduced in 2000 and the Swedish .338 Norma Magnum (.338 NM) cartridge introduced in 2008 are probably the closest currently (2018) commercially available ballistic twins of the .338-378 Weatherby Magnum. The Lapua and Norma cartridges are rimless and the Remington has a rebated rim.

References

{{DEFAULTSORT:338-378 Weatherby Magnum Pistol and rifle cartridges Weatherby Magnum rifle cartridges Wildcat cartridges

See also

References