338 Winchester Magnum
.Theย .338 Winchester Magnumย is a .338ย in (8.6ย mm) caliber, belted, rimless, bottlenecked cartridge introduced in 1958 byย Winchester Repeating Arms. It is based on the blown-out, shortened .375 H&H Magnum.[2]ย The .338ย in (8.6ย mm) is the caliber at which medium-bore cartridges are considered to begin.
The .338 Winchester Magnum is the first choice among professionalย brown bearย (specificallyย grizzly bear)ย guidesย inย Alaskaย to back up clients where a powerful stopping caliber is required on charging bears.[3]ย It is also the most popular medium-bore cartridge in North America[4]ย and has the most widely available choice in rifles among medium bore rifles.
The action length is the same as a .30-06, and most major rifle manufacturers in the United States chamber rifles for the cartridge including the semi-automaticย Browning BARย Mk II Safari, making it a very powerful combination against charging dangerous game.[5][6]
The cartridge was intended for larger North American big-game species and has found use as for the hunting of thin-skinned African plains-game species.[1]
The .338 Winchester Magnum traces its heritage to the experiments conducted by Charles O’Neil, Elmer Keith and Don Hopkins with cartridges firing .333ย in (8.5ย mm) bullets in the late 1940s.
The use of .333ย in (8.5ย mm) bullets may seem odd today but at the time this was the standard diameter of European .33 caliber bullets which were more common than the .338ย in (8.6ย mm) diameter bullets used in cartridges such as the .33 Winchester.
Furthermore, the .333ย in (8.5ย mm) were available in heavier weights than the .338ย in (8.6ย mm) bullets. O’Neil, Keith and Hopkins experiments led to the creation of the .333 OKH, which was based on theย .30-06 Springfieldย case necked up to accept .33 caliber bullets and the .334 OKH which used a shortened .375 H&H Magnum necked down to accept the same bullets.
The .338 Winchester Magnum was introduced in 1958 together with theย .264 Winchester Magnumย and theย .458 Winchester Magnum, all of which used a common case design based on the .375 H&H Magnum case blown out and shortened to 2.500ย in (63.5ย mm), much like the .334 OKH
. When the cartridge was introduced, Winchester offered a 200ย gr (13ย g) at 3,000ย ft/s (910ย m/s), a 250ย gr (16ย g) at 2,700ย ft/s (820ย m/s) and a 300ย gr (19ย g) at 2,450ย ft/s (750ย m/s). Sometime later, Winchester introduced the Winchester Model 70 Alaskan chambered for the cartridge.
This chambering left little doubt that the cartridge was intended for big heavy dangerous game.
The .338 Winchester Magnum follows the modern cartridge designs in that the cartridge case features a case with minimal taper so as to maximize case capacity yet providing reliable feeding and extraction.
The .338 Winchester Magnum is based on the .375 H&H Magnum, which was shortened to 2.500ย in (63.5ย mm), blown out and necked down to hold a .338ย in (8.6ย mm) bullet. The case has a capacity of 86.0 grain of H2O (5.58ย cm3).
The cartridge follows the design of the standard length Weatherby Magnum cartridges such as theย .257 Weatherby Magnum,ย .270 Weatherby Magnumย and theย 7 mm Weatherby Magnumย for which Winchester had supplied basic brass until 1948.
Performance[edit]
This cartridge is able to push a 225-grain (14.6ย g)ย bulletย toย velocitiesย of 2,800ย ft/s (850ย m/s), generating 3,918ย ftโ lbf (5,312ย J),[7]ย providing energy values at 200 yards that are roughly equivalent to theย .30-06 Springfield‘s energy values[8]ย atย muzzle. Bullets are available in a very wide range of designs and weights ranging from 150[9]ย to 300 grains.ย SAAMIย pressure level is 64,000ย psi.
338 Winchester Magnum is capable of launching heavier bullets than the .30 caliber (7.62mm) cartridges. The most common bullets loaded for the .338 Winchester range from 200ย gr (13ย g) to 250ย gr (16ย g). Typical bullet weights for factory ammunition are 200ย gr (13ย g), 210ย gr (14ย g), 225ย gr (14.6ย g) and the 250ย gr (16ย g).
Typical velocities for these bullet weights range from 2,960ย ft/s (900ย m/s) for the 200ย gr (13ย g) to about 2,660ย ft/s (810ย m/s) for the 250ย gr (16ย g) bullet each generating approximately 3,900ย ftโ lbf (5,300ย J) of energy.
This is approximately 25% more energy generated than the 30-06 Springfield.
Key Specifications
- Item Number: 97339
- Mfg. Number: P338B2
- UPC: 029465084837
- Caliber: .338 Winchester Magnum
- Bullet Weight: 250 grain
- Bullet Style: NP
- Muzzle Velocity: 2,660 FPS
- Muzzle Energy: 3,925 ft.-lbs.
- Case Type: Nickel plated
- Primer Type: Boxer, reloadable
- Corrosive: No
- Rounds: 20





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