.338 Winchester Magnum

The .338 Winchester Magnum is a .338 in caliber belted rimless bottlenecked cartridge introduced in 1958 by Winchester Repeating Arms. It is based on the blown out, shortened .375 H&H Magnum. The .338 in is the caliber at which medium bore cartridges are considered to begin. Hence, the .338 Winchester Magnum is considered a first option for those requiring a medium bore cartridge. It is the most popular medium bore cartridge in North America and one of the most popular magnum cartridges currently available. 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.

Cartridge history
The .338 Winchester Magnum traces its heritage to the experiments conducted by Charles O’Neil, Elmer Keith and Don Hopkins with cartridges firing .333 in bullets in the late 1940s. The use of .333 in 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 .338 in diameter bullets used in cartridges such as the .33 Winchester. Furthermore the .333 in were available in heavier weights than the .338 in bullets. O’Neil, Keith and Hopkins experiments lead to the creation of the .333 OKH, which was based on the .30-06 Springfield 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 the .264 Winchester Magnum and the .458 Winchester magnum; all of which used a common case design based on the .375 H&H Magnum case blown out and shortened to 2.500 in much like the .334 OKH. When the cartridge was introduced, Winchester offered a 200 gr at 3000 ft/s, a 250 gr at 2700 ft/s and a 300 gr at 2450 ft/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.

Design and specifications
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 2.500 in, blown out and necked down to hold a .338 in bullet. The case has a capacity of 86.0 grain of H2O (5.58 cm3). The cartridge follows the design of the standard length Weatherby Magnum cartridges such as the .257 Weatherby Magnum, .270 Weatherby Magnum and the 7 mm Weatherby Magnum for which Winchester had supplied basic brass until 1948.

Both the Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives(CIP) and the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) govern and regulate the specifications regarding the .338 Winchester Magnum.


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SAAMI and the CIP recommend a 6 groove barrel with a twist rate of one revolution in 10 in barrel with a bore Ø of .330 in and a grove diameter of Ø of .330 in with each groove having a width of .110 in. The SAAMI recommended average peak pressure for the cartridge is 65000 psi. The CIP enforces a 4300 bar pressure limit for the cartridge.

Performance
This cartridge is able to push a 225 gr bullet to velocities of 2,800 ft/s (853.44 m/s), generating 3,918 ft·lbf (5258 J), providing energy values at 200 yards that are roughly equivalent to the .30-06 Springfield's energy values at muzzle. Bullets are available in a very wide range of designs and weights ranging from 150 to 300 grains. SAAMI pressure level is 64,000 p.s.i.

The .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 200 gr to 250 gr. Typical bullet weights for factory ammunition are 200 gr, 210 gr, 225 gr and the 250 gr. Typical velocities for these bullet weights range from 2960 ft/s for the 200 gr to about 2660 ft/s for the 250 gr bullet each generating approximately 3900 ftlbf of energy. This is approximately 25% more energy generated than the 30-06 Springfield.

Winchester’s 200 gr Ballistic Silvertip ammunition (SBST338) retains over 1600 ftlbf at 625 yd and has 1000 ftlbf energy at 800 yd. Winchester’s Combined Technologies Accubond ammunition (S338CT) extend the range for these energy levels even further to 675 yd and 850 yd respectively.

The recoil of this caliber is quite heavy, with about 31 ftlbf of recoil energy in a 9 lb (4.08 kg) rifle. This is about twice as much as the recoil from an average .308 Winchester. Strong recoil like this can be mitigated with the use of properly designed stocks and recoil pads. By comparison, this cartridge has less recoil than other more powerful .338-caliber rifles such as the .338 RUM, .340 Weatherby and .338 Lapua.

Use of a muzzle brake can reduce the recoil from these rifles. Use of brakes will, however, increase greatly the blast noise through the diversion of muzzle gases to the sides.

Sporting usage
When the .338 Winchester was introduced there was a general preference for heavier bullet weights between 250 - 300 gr. However, since that time preferred bullet weights have decreased to weights between 200 - 225 gr. This is due in part to the bullet technology available today. Lighter bullets made today are able to hold together and penetrate deeper than heavier bullets of the past.

In North America, the .338 Winchester Magnum is most commonly used for the hunting of larger deer species such as elk and moose. Due to its popularity with elk hunters and its effectiveness as an elk cartridge it is known as the “King of the Elk Cartridges”. Bullets ranging between 200 - 225 gr are generally preferred for the hunting of elk and even moose.

Apart from the larger deer species, the .338 Winchester Magnum is often used for the hunting of and defense against the great bears such as the grizzly, polar and brown bears. It is often carried by fishermen, hunters and guides in Alaska and Canada for protection as encounters with these larger bear species can be common.

The .338 Winchester Magnum can be considered a good all-round plains game hunting rifle in Africa. It has also been found to be effective against the big cats where hunting allows for the use of the cartridge.

Rifles and ammunition
Due to the cartridge’s popularity all North American rifle manufacturers offer rifles chambered in the .338 Winchester Magnum. Ruger, Browning, Kimber, Remington, Savage, Weatherby, Mossberg, Howa and Winchester chamber the cartridge in several product lines. Almost all custom rifle makers in the United States and Canada produce .338 Winchester rifles. In European rifle makers Blaser, Mauser, Sako and Tikka also manufacture rifles for this cartridge. The large number of rifle choices available in the .338 Winchester Magnum offers the rifleman a greater choice in available rifle platforms.

All North American ammunition makers offer several loadings of the .338 Winchester Magnum to the public for sale. At this point in time Federal has six in their Vital-Shok and Fusion ammunition lines, Hornady has five, including four in their Superformance ammunition which is putting an end to the light magnum and heavy magnum line of ammo but adds up to 200 ft/s more without added recoil or muzzle blast. The 185 gr. GMX (gliding metal expanding) round has the following performance: 3080 ft/s at the muzzle, 2850 ft/s at 100 yards, 3,896 ft⋅lbf (5,282 J) of kinetic energy at the muzzle and 3,337 ft⋅lbf (4,524 J) at 100 yards. 200 gr. SST, 225 gr. interbond, 225 gr. SST are all excellent big game rounds, and the 185 gr. is a wonderful deer round. Remington and Winchester offer four loadings each for the cartridge. Several smaller ammunition including Cor-Bon and Double Tap also manufacture loaded ammunition.