And just in case your .460 proves inadequate...
This thread needed a 50BMG anyway, just because.
Posted on 10/30/2003 12:02:51 PM PST by 45Auto
The 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 will also apply to a European hunter seeking game including deer, feral pigs, and Scandinavian moose, or anyone hunting similar size game worldwide. This person must be a reloader willing to develop loads appropriate for medium and large thin-skinned game.
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 (ME) 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 would require three distinct levels of power. One should be a light load of moderate recoil, appropriate for deer and other medium size big game. This load should be essentially equivalent to the standard .45-70 factory loads suitable for use in all types of .45-70 rifles. These loads typically drive a 300 grain JHP bullet at a MV of 1810-1880 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 loads intended for modern lever action rifles such as the Marlin Model 1895. These loads operate at higher pressure than .45-70 factory loads and are unsafe in original Trapdoor or replica .45-70 rifles of similar strength. Such loads, with suitable bullets, are recommended for large game such as the North American elk. These loads can drive a 300 grain bullet about 200-300 fps faster than .45-70 factory loads and are loaded to a MAP of up to 40,000 cup. (350 and 400 grain bullets can also be used at similar pressure.)
The third, even higher pressure, load should drive a 350 to 400 grain bullet at the maximum velocity possible in a modern .45-70 rifle, such as a Ruger No. 1. These are loads suitable for the heaviest North American game, and most of the heavy game in the world. They will achieve MV's in the 2100 fps region with a 350 grain bullet, and can develop pressures as high as 50,000 cup. Such loads deliver heavy recoil, on the order of a powerful medium bore rifle, but still much less than full power .458 Magnum loads.
The .45-70 is the oldest rifle cartridge still in production and wide scale use. It was introduced in the 1873 Springfield "Trapdoor" 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 SAAMI maximum average pressure (MAP) limit for the .45-70 is 28,000 cup.
However, most reloading manuals have special sections where they list .45-70 loads for use only in strong, newly manufactured lever action rifles, typically the Marlin (336 derived) Model 1895 rifle. These loads produce pressures from 28,000 cup to as high as 40,000 cup.
Some reloading manuals have a third section devoted to .45-70 loads intended for exceptionally strong rifles such as the modern Browning, Dakota, and Ruger falling block single shots. These loads can run in the 35,000 to 50,000 cup range.
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 loaded to a MAP of 53,000 cup.
The .458 was intended to duplicate the ballistics of the 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 focus on loads developed for soft point expanding bullets designed for .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 or 350 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) 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. The SD of the 300 grain .458" bullet is .204; the SD of the 350 grain .458" bullet is .238.
The standard 300 grain .458" bullet has a SD generally regarded as suitable for antelope, deer, feral pigs, and black bear (CXP2 class game). Premium controlled expansion .300 grain bullets that offer deeper than normal penetration can also be used for larger game such as the North American elk and Scandinavian alg. 350 grain .458" bullets have a SD often recommended for elk and moose (CXP3 class game).
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 a medium game load. The Hornady 300 grain JHP bullet is intended for best performance when launched at muzzle velocities between 1600 and 2100 fps. For medium game like deer, most antelope, and feral pigs we can do no better than to duplicate the standard .45-70 factory loads. As we have already seen, .45-70 factory loads drive a 300 grain JHP bullet at claimed MV's of 1810-1880 fps. The muzzle energy (ME) of these loads ranges from 2182 ft. lbs. to 2355 ft. lbs.
Reloaders will have no difficulty finding data to duplicate such loads in all of the popular reloading manuals. The approximate recoil energy of a 9 pound .45-70 rifle shooting a 300 grain bullet at a MV of 1850 fps is a manageable 18.7 ft. lbs.
Reloading data for using 300 grain .45-70 bullets in the .458 Magnum is not as wide spread, but it is available. The fifth 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. It is interesting that three of these powders, IMR 4198, H4198, and Viht. N-120 are also among the powders listed for .45-70 loads with the same bullet at similar velocity. The recoil energy of these loads averages about 18.1 ft. lbs. when fired in a .458 Magnum rifle weighing 9 pounds.
A 300 grain JHP bullet at a MV of approximately 1850 fps is our chosen medium 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 reasonable choice for hunting medium game at woods ranges.
For our intermediate power load, the Hornady Handbook of Cartridge Reloading shows that in the .45-70 their 300 grain bullet can be driven to a MV of 2100 fps with maximum loads of two powders, IMR 4198 and Viht. N-130. The same reloading manual shows that four different powders (including IMR 4198) can be used to drive the 300 grain bullet to a MV of 2100 fps in the .458 Win. Mag.
At a MV of 2100 fps a 300 grain bullet develops ME of 2937 ft. lbs. At 100 yards the remaining energy of the Hornady bullet is 1978 ft. lbs.
The recoil of these loads, at a MV 250 fps faster than the standard .45-70 load using a bullet of the same weight, is naturally greater. In a 9 pound .45-70 rifle the recoil energy should be about 24.4 ft. lbs. In a .458 Magnum rifle of equal weight the recoil energy should be about 23.8 ft. lbs. (According the Hornady Handbook, the .458 Magnum actually uses less powder to achieve this velocity than the .45-70, probably because their .45-70 Marlin test rifle had a 22" barrel and their .458 test rifle had a 24" barrel.)
For tough, heavy game we can use 350 grain bullets. Hornady specifically recommends their 350 grain bullet for large and dangerous game. This 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 this bullet can be driven to a MV of 2200 fps by three powders (IMR 4198, Viht. N-130, and IMR 3031) in the strongest .45-70 rifles. That handbook also shows that the 350 grain bullet can be driven to the same velocities in the .458 Winchester Magnum cartridge by eight different powders, including all three of the powders used in the .45-70.
At a MV of 2200 fps a 350 grain bullet has a ME of 3761 ft. lbs. The 100 yard energy is 2507 ft. lbs.
The recoil of such a load in a 9 pound .45-70 rifle is about 34.9 ft. lbs. In a 9 pound .458 Magnum rifle the recoil will run about 35.9 ft. lbs. That is a lot of kick, about like that of a typical .358 Norma Magnum rifle, 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 worth comparing 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 is as follows.
300 grain at 1850 fps = 170 yards
300 grain at 2100 fps = 190 yards
350 grain at 2200 fps = 197 yards
The hardest factor to quantify is killing power. We know that energy, penetration, and bullet frontal area are all important factors in killing power, but not exactly what is the best blend of these factors. What is clear is that the same bullet at the same velocity will have identical killing power, whether fired from a .45-70 or a .458 Magnum. Of course, this article is about the .458 and .45-70 loaded to equal performance. 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. Full power .458 Magnum loads with proper 465-500 grain bullets have proven suitable for the largest game on earth, the African elephant.
One indication of killing power is the "Optimal Game Weight Formula" developed by Edward A. Matunas. While undoubtedly not perfect, this formula at least gives an approximate idea of the capability of the cartridges under discussion. I calculated the maximum optimal game weight for each load at 100 yards.
300 grain at 1850 fps - 474 pounds at 100 yards.
300 grain at 2100 fps - 706 pounds at 100 yards.
350 grain at 2200 fps - 1088 pounds at 100 yards.
The .458 Win. Mag. has the smallest case capacity and the biggest bullet selection of any of the "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 modern smokeless powders, 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.
New and used 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 even more common on today's market.
For the reloader who wants to own and shoot a big bore rifle, the .45-70 and .458 Winchester Magnum seems like the best candidates. The reloader can assemble reasonable loads for everything from whitetail deer to polar bear and moose at considerable savings in both cost and recoil compared to most other big bore buffalo and elephant cartridges.
Gonna look into the Ruger 77 version in that flavor as a companion to my Numbah 1 in .460 Weatherby Mag.
Stay Safe !
Randy Garrett makes the best 45-70 ammo for the number 1 or the 1895 Marlin lever gun. Hammerhead rounds keep the hunter higher on the food chain with regard to dangerous game IMO.
Stay Safe !
And just in case your .460 proves inadequate...
This thread needed a 50BMG anyway, just because.
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