RELOADING
The .458 Winchester Magnum
Designed for Africa but All-American in its impact, this safari stopper is still a bigbore to reckon with.
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| Alliant: | RL-7, RL-12 |
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| Hodgdon: | H322, H335, H44198, H4895, Benchmark, Varget |
| IMR: | IMR4320, IMR4895, IMR4064, IMR3031 |
| Ramshot: | TAC |
| VihtaVuori: | VV135 |
| Winchester: | WW748 |
.458 Winchester Magnum (Suitable Powders)
A few years after the end of World War II, Africa's professional hunters faced a growing dilemma--a shortage of ammo for their fine British double rifles. Most ammo on hand was from prewar stock, and Kynoch, the sole source of ammo for the big stoppers, had decided to stop production for most of them.
Just when the shortage was becoming critical, Winchester came to the rescue in 1956 with the revolutionary .458 Winchester Magnum--an honest-to-God elephant caliber. It was chambered in the Winchester Model 70 African bolt action, and the combination became an instant success among African professionals and their clients alike. Today it's a reasonable certainty that more African professional hunters use a .458 than any other cartridge.
The introduction of the .458 was a watershed event that changed the face of American sporting arms forever, and it had almost nothing to do with the cartridge's demonstrated effectiveness on African game.
The impact of the .458 was that it sired a new class of American magnum cartridges suitable for .30-06-length actions, including the .338 and .264 Winchester Magnums, and their success spawned the 7mm Remington Magnum. The high muzzle velocity offered by these new cartridges caught the imagination of American shooters, and "magnumania" was born.
Also, the .458 had braggin' rights as America's bigbore "stopper caliber," suitable for the heavyweight division of Africa's Big Five dangerous-game animals. A 500-grain bullet at between 2,000 and 2,100 fps made the .458 Magnum nearly equal to the .470 Nitro Express, a classic double-rifle cartridge that launches a 500-grain bullet at about 2,150 fps.
The first two shots from a good bolt action chambered for the .458 Mag were a bit slower than a "quick left and right" from a double, however; many professionals preferred "three shots in the magazine and one up the pipe" with a bolt action. This additional firepower could be crucial during culling operations or in the event of a charge.
Over the years, detractors have claimed that the .458 has serious drawbacks as a stopper. One argument says the .458 is a bit short on powder capacity because of its 2 1/2-inch case length. The result, it is said, is that in the real world the .458 falls far short of its advertised muzzle velocity, delivering only 1,900 fps or so in most rifles.
A second criticism talks about "squib loads" that barely penetrate the thick, tough skin of a Cape buffalo or other "big heavies." This is attributed to compressed powder charges that clump together and burn erratically.
The critics' answer in both cases is a cartridge that has enough additional case capacity to achieve a significantly higher muzzle velocity without a highly compressed powder charge, such as the somewhat longer .458 Lott. Without doubt, the .458 Lott is a fine stopper, and you might prefer the additional velocity, energy and recoil. However, my range testing shows that you need not feel poorly armed if you carry a .458 Winchester after Cape buffalo, elephant or any other big, truculent beast.
My test rifle was a Ruger No. 1H with the standard 24-inch barrel. The rifle had started out as a barreled action, and a previous owner had mated it to an extremely plain walnut stock. It doesn't look like much, but it shoots just fine.
I wired the test rifle for my Oehler Model 43 Personal Ballistics Laboratory. I then fired factory ammo to obtain pressure baseline data. Five-round averages for both loads were slightly higher than advertised velocities. The Winchester 510-grain softpoints launched at 2,070 fps (30 fps over spec), and the Federal 500-grain Trophy Bonded 500-grain solids went slightly higher�2,127 fps instead of 2,090.
When you handload for the .458, seating depth is your controlling factor. The .458's prodigious recoil makes it necessary to crimp heavily into the bullet's cannelure. Depending on which brand and weight of bullet you use, this might reduce the available powder capacity for a given load. Loads listed in the table on this page were compiled with this in mind.
Bullet weights range from 300 grains up to 600 grains for the Barnes Original RNSP. However, the lighter bullets are designed to be used in .45-70 or even lighter cartridges and may not yield optimum performance in the .458. For this reason, loads listed here begin with the excellent 350-grain bullets from Barnes and Hornady.
The .458 Winchester Magnum is considerably more powerful than necessary for North American game. But more than one Alaskan bear guide carries a .458 to back up his clients in the alder tangles of the Alaskan peninsula or Kodiak Island. For other game such as American bison, the .458 is an excellent stand-in for the old 19th century buffalo calibers.
If you are a dyed-in-the-wool gun crank, you need a .458 even if you never expect to go on safari on the Dark Continent. It has the mystique of adventure, so that just touching off a few solids at the local shooting range will draw a crowd. Some shooters prefer to steer clear of heavy-recoiling calibers, but like those who ride mechanical bulls, others will enjoy the challenge of trying to tame the beast.
WARNING: The loads shown here are safe only in the guns for which they were developed. Neither the author nor InterMedia Outdoors assumes any liability for accidents or injury resulting from the use or misuse of this data.
© 2009 Intermedia Outdoors. All rights reserved.
