From Wikipedia, the free encyclopedia:
"The .458 Winchester Magnum is a rifle cartridge introduced 1956 by Winchester. The cartridge case is based on the .375 H&H case shortened to 2.5 in (64 mm), and "blown out" (case opening enlarged) to accept a bullet of .458 inch (11.6 mm) diameter. The developers of the .458 Winchester Magnum sought to duplicate the ballistics of the 450 Nitro Express and 470 Nitro Express, in a cartridge that would fit in a standard bolt-action rifle. With good handloads one can expect approximately 2,170 feet (660 m) per second (660 m/s) using 500 grain (32.4 g) bullets (achieved using a barrel 24 inches (610 mm) in length). Though somewhat overpowered for North American game like deer and elk, the .458 is most useful for African game like Cape buffalo and lions. The 458 Winchester Magnum is the largest of a family of "short magnums" that include the .338 Winchester Magnum, .264 Winchester Magnum, and later the .300 Winchester Magnum.
Winchester currently offers ammunition in the traditional 510 gr (33 g) Soft Point and the new 500 gr (32 g) Nosler Partition and Nosler Solid. The Winchester 500 gr (32 g) loading has a muzzle velocity of 2,240 ft/s (680 m/s) and muzzle energy of 5570 foot pounds. Hornady offers what they call a "heavy magnum" loading that features a 500 grain (32.4 g) bullet with a velocity of approx 2,260 feet (690 m) per second (690 m/s). They use a special double-based cooler burning propellant ("powder") not available to the public for handloading. This innovative loading allows the .458 Winchester Magnum to attain 5670 foot pounds of muzzle energy. Federal Cartridge is now loading a 500-grain (32 g) Barnes X bullet with a sectional density and ballistic coefficient that allows it to maintain approximately 2000 foot pounds of energy at 500 yards (460 m) and a flatter trajectory that has never been attained with this cartridge and bullet weight. Numerous companies offer rifles in this caliber, including the Winchester Model 70.
The rounds for the .458 Win mag are more expensive than cartridges like the popular .30-06, making handloading a worthwhile effort. Though more expensive than deer hunting ammunition, the .458 Winchester Magnum is significantly less expensive than its competitors. For many decades the .458 has been the most popular rifle cartridge of professional hunters in Africa because of its price and availability. When British ammunition companies, including Kynoch, began closing in the 1960s, Winchester and the .458 Winchester Magnum filled the gap left behind. For decades the .458 Win mag has been the most popular choice of professional hunters in Africa who pursue heavy dangerous game.
The recoil of the factory loads is about 70 foot pounds. Handloads can be made that will make this cartridge more comfortable to shoot, for example using a 300-grain (19 g) cast lead bullet at 1,282 ft/s (391 m/s). This loading mimics the 45/70 in both power and recoil."
.458 Winchester Magnum. (2009, January 23). In Wikipedia, The Free Encyclopedia. Retrieved 14:05, March 23, 2009, from http://en.wikipedia.org/w/index.php?title=.458_Winchester_Magnum&oldid=265886515