Compared: The .45-70 Government and .458 Winchester Magnum for North American and European Hunting
By Chuck Hawks
This article is written for the hunter who wishes to hunt medium and large game with a big bore rifle. He or she is not looking for an elephant rifle, but rather a big bore rifle with adequate killing power for hunting all North American game at typical woods ranges (less than 200 yards). The same basic criteria would also apply to a European hunter seeking game such as deer, wild boar, and Scandinavian moose, or anyone hunting similar size game worldwide. This person must be a reloader willing to develop appropriate loads.
This is not a comparison of two essentially similar cartridges. It is about handloading two dissimilar .45 caliber cartridges to produce equally appropriate loads for hunting medium and large game at recoil levels tolerable to most shooters. This requires light .458 Winchester Magnum loads, and (in some cases) heavy .45-70 loads, and considerably extends the usefulness of both cartridges. It is made possible by the development of modern smokeless powders that enormously extend the versatility of older black powder rifle cartridges like the .45-70 in suitably strong rifles.
There is no doubt that with full power loads the .458 Winchester Magnum is the more powerful cartridge. Its greater case capacity allows muzzle velocities (MV) approximately 300 fps faster than even the heaviest .45-70 loads (which are restricted to strong bolt action and single shot rifles only). This translates to an equally great advantage in muzzle energy (ME), which amounts to about 1100 ft. lbs. with a 350 grain bullet.
But it is also true that the heaviest .45-70 handloads tread on the lower reaches of .458 Magnum reloads. And that these .45-70 reloads are sufficiently powerful for all North American big game.
So might the reverse also be possible? That is, handloading the .458 Magnum to .45-70 levels specifically for use on the common types of North American and European big game? After all, many .458 "Safari" rifles are no heavier than the strong .45-70 single shot rifles that frequently weigh about 9 pounds with a scope.
This comparison will require two distinct levels of power, from opposite ends of the .45-70 spectrum. One should be a light load of moderate recoil, appropriate for deer and other CXP2 class big game. This load should be essentially equivalent to the standard .45-70 loads suitable for use in all types of .45-70 rifles. These loads typically drive a 300 grain JHP bullet at a MV of about 1850 fps or a 400 grain bullet to 1400 fps. Modern .45-70 factory loads are usually held to a modest maximum average pressure (MAP) of 21,000 cup in deference to the ancient .45-70 rifles still in use, and modern "Trapdoor Springfield" replicas.
The second level of power should approximate .45-70 reloads intended for use only in strong, modern arms such as the Dakota Model 10, Ruger No. 1 and Browning 1885 High Wall falling block rifles. These loads operate at much higher pressure than standard .45-70 factory loads and are unsafe in lever action or "Trapdoor" type rifles. Such loads are recommended for the largest CXP3 class big game such as elk, moose, and grizzly bear. They typically drive a 350 grain bullet to a MV of around 2100 fps and are loaded to a MAP of up to 50,000 cup.
The .45-70 Government
The .45-70 is the oldest rifle cartridge still in production and wide scale use. It was introduced in the 1873 Springfield rifle, and adopted by the U.S. Army. It served as both a military and civilian cartridge on the American western frontier, and helped to decimate the immense heads of buffalo that once roamed the land. The American bison is a very big animal, on the order of 1600 pounds on the hoof, so even with black powder loads the .45-70 clearly possessed serious killing power with heavy bullets.
The .45-70 is based on a rimmed, straight walled case of the type most suitable for single shot rifles and repeating rifles using a tubular magazine, such as the Winchester Model 1886 and Marlin Model 1895 lever actions. Its name comes from its .45 caliber bullet (it uses the same .458" diameter bullets as the much later .458 Mag.) and the weight of black powder (70 grains) once used in standard loads behind a 405 grain bullet. This sort of nomenclature was common in the days of black powder cartridges. The official SAAMI maximum average pressure (MAP) limit for the .45-70 is 28,000 cup.
The .458 Winchester Magnum
Winchester introduced the .458 Winchester Magnum cartridge in 1958. It is based on a straight, shortened .375 H&H belted magnum case necked-up to accept .458" bullets. It is commercially loaded to a MAP of 53,000 cup.
The .458 was intended to duplicate the ballistics of the most popular British elephant rifle calibers in a cartridge that would work in standard (.30-06) length bolt action rifles. It is also available in some of the same strong single shot rifles offered in .45-70. The .458 Winchester Magnum has become the world's most popular cartridge for dangerous thick-skinned game.
Winchester's .458 Magnum was designed to drive a 500 grain bullet at a MV of about 2100 fps with ME of 4895 ft. lbs. Factory loads are available from A-Square, Federal, Hornady, Norma, Remington, Speer, and Winchester. These include bullet weights ranging from 350 grains to 510 grains at velocities ranging from 2470 fps (350 grain bullet) to 2040 fps (510 grain bullet). Federal Premium Safari loads, for example, drive 500 grain solid or controlled expansion bullets at a MV of 2090 fps.
Most .458 Magnum "safari" loads use bullets too tough for normal expansion on thin-skinned game. Most .45-70 loads, however, use bullets designed for proper expansion on medium to large size thin-skinned game. So for our purposes we will ignore the .45 caliber FMJ "solid" bullets and ultra-tough controlled expansion bullets like the 500 grain Trophy Bonded Bear Claw. Instead we will concentrate on bullets designed to expand properly at .45-70 impact velocities.
The handloader has a good selection of jacketed 300 grain, 350 grain, 400-405 grain and 500 grain .45 caliber rifle bullets from which to choose. Since all North American and European game can humanely be taken with 300-400 grain bullets, we will focus on those bullet weights. Specifically, for the purposes of this article, I am going to use the 300 grain Hornady Flat Hollow Point (#4500), Speer 400 grain Flat Nose Soft Point (#2479), and the 350 grain Hornady Round Nose (#4502) bullets. Obviously, since the .45-70 and .458 Winchester Magnum can use the same bullets, the sectional density (SD) and bullet frontal area will be exactly the same for either caliber.
Sectional density is computed by dividing a bullet's weight (in pounds) by the square of its diameter (in inches). SD is important because it is one of the major factors in bullet penetration. The higher the sectional density figure the better the penetration, all other factors being equal. In .458" caliber the SD of a 300 grain bullet is .204, the SD of a 350 grain bullet is .238, and the SD of a 400 grain bullet is .272.
The standard 300 grain .458" bullet has a SD generally regarded as suitable for antelope, deer, feral pigs, goats, sheep, and black bear (CXP2 class game). 350-400 grain .458" bullets have sectional densities normally recommended for a wide variety of CXP2 and CXP3 class game, from whitetail deer to moose.
The cross-sectional area (frontal area) of a bullet is also important. The greater the frontal area, the bigger the hole it makes in the target. The frontal area of all .458" bullets, regardless of weight, is 0.1647 square inch.
Now let's look at loads for CXP2 class game. For medium game like deer, most antelope, and feral pigs we can do no better than to duplicate the standard velocity .45-70 loads. As we have already seen, standard .45-70 loads drive a 300 grain hollow point bullet at a MV of around 1850 fps and a 400 grain soft point bullet at a MV of about 1400 fps. The muzzle energy (ME) of these loads ranges from about 1740 ft. lbs. for the 400 grain bullet to 2281 ft. lbs. for the faster 300 grain bullet.
Handloaders will have no difficulty finding data for such loads in the .45-70 section of all of the popular reloading manuals. The approximate recoil energy of a 9 pound .45-70 rifle shooting a 400 grain bullet at a MV of 1400 fps is 19.7 ft. lbs. The recoil energy figure for the 300 grain bullet is about one ft. lb. less.
Reloading data for using 300 grain bullets in the .458 Magnum is not as wide spread, but it is available. The sixth edition of the Hornady Handbook of Cartridge Reloading lists .458 Winchester Magnum loads using their 300 grain JHP bullet at a minimum of 1850 fps with four different powders. The recoil energy of these loads averages about 18.1 ft. lbs. when fired in a .458 Magnum rifle weighing 9 pounds.Data in the Speer Reloading Manual No. 13 indicates that a reduced load for the .458 Magnum using SR 4759 powder can drive their 400 grain bullet at about 1400 fps. I have found this to be an excellent reduced power load in my .458 Magnum rifle. According to the "Expanded Rifle Recoil Table," the recoil energy of this load is only 16.1 ft. lbs.
A 300-400 grain bullet at standard .45-70 velocities is our chosen CXP2 class game load, and both the .45-70 and .458 Magnum can do the job with less than 20 ft. lbs. of recoil energy. Most reasonably experienced shooters will be able to handle that amount of recoil without too much problem. Such loads make these big bore calibers a viable choice for hunting medium game at woods ranges.
For large CXP3 class game we can use 350 grain bullets. Hornady and Speer both specifically recommend their 350 grain bullets for large and dangerous game. The Hornady #4502 is a round nose InterLock bullet designed for best performance at muzzle velocities from 1800-2900 fps.
The Hornady Handbook of Cartridge Reloading shows that in the .45-70 their 350 grain bullets can be driven to a MV of 2100 fps with four different powders. The same reloading manual shows that eight powders, including all four of the powders used in the .45-70, can be used to drive a 350 grain bullet to a MV of 2100 fps in the .458 Win. Mag.
At a MV of 2100 fps a 350 grain bullet has a ME of 3427 ft. lbs. The 100 yard energy is 2268 ft. lbs.
The recoil of such a load in a 9 pound .45-70 rifle is about 32.8 ft. lbs. In a 9 pound .458 Magnum rifle the recoil will run about 34.7 ft. lbs. That is a lot of kick, but only a little more than half the recoil of a full power .458 Magnum factory load.
Flat trajectory is not usually the reason for purchasing a big bore rifle, but it is interesting to compare the maximum point blank range (MPBR) of the three different loads we are considering. In the field it makes sense to zero a hunting rifle for its maximum point blank range. Here are the numbers, calculated for a line of sight 1.5" over the bore (as with a low mounted scope). These figures will apply to either a .45-70 or .458 Magnum rifle using the same bullets at the same velocity. If the bullet is allowed to deviate no more than 3" above or below the line of sight the MPBR of our three loads should be as follows.
Obviously, the same bullet at the same velocity will have identical killing power, whether fired from a .45-70 or a .458 Magnum. This article is about the .458 and .45-70 loaded to equal performance, but if one wants more killing power, the .458 Magnum has a great deal of reserve potential that can be realized merely by loading to higher velocity.
Just how effective are our selected loads? One indication of killing power is the "Optimal Game Weight Formula" developed by Edward A. Matunas. While undoubtedly not perfect, this formula can be used to compare hunting loads in terms of the size of the animal for which they are suited. I calculated the maximum optimal game weight for the three loads we have been discussing at a distance of 100 yards.
The .458 Win. Mag. has the smallest case capacity and the biggest bullet selection of any of the common "elephant rifle" cartridges, so it follows that it has the greatest diversity of reduced power, moderate recoil reloads. And the .45-70 case, although smaller than the .458 Magnum case, was designed for bulky black powder. Consequently, when loaded with much denser smokeless powder, the .45-70 has considerably greater performance potential than was originally envisioned.
Ammunition availability is always an important consideration for any rifle, and in this area the .45-70 and .458 Winchester Magnum are exceptional compared to all other big bore rifle cartridges. .45-70 and .458 Magnum factory loaded ammunition is both more economical and more widely available than any other big bore rifle cartridges. Equally important, so are reloading dies, brass, bullets and other reloading supplies.
Rifles chambered for the .45-70 and .458 Win. Mag. cartridges are widely available. Because it was designed for standard length magnum actions, many manufacturers can and do chamber their bolt action rifles for the .458 Magnum. And .45-70 rifles of various sorts (primarily lever action and single shot models) are also common in today's marketplace.
For the reloader who wants to own and shoot a big bore rifle, the .45-70 and .458 Winchester Magnum seem like the best candidates. The reloader can assemble reasonable loads for everything from whitetail deer to brown bear and moose at considerable savings in both cost and recoil compared to most other big bore hunting cartridges.
Copyright 2003, 2012 by Chuck Hawks. All rights reserved.