Compared: The .416 Rigby and .416 Remington Magnum vs. .458 Winchester Magnum
By Chuck Hawks
The .416 Rigby was a proprietary cartridge developed by John Rigby of the UK in 1911. It is based on a huge rimless case (no belt) designed specifically for Magnum Mauser actions. It has always been loaded to relatively low pressure (C.I.P. maximum average pressure is 41,364 cup) for easy extraction in very hot climates, principally Africa.
Jack O'Connor helped to popularize the cartridge in the U.S., and introduced it to Roy Weatherby, who used a belted version of the Rigby case as the basis for his .378, .416, and .460 Magnum calibers. British .416 ammunition was loaded with a 410 grain bullet at a muzzle velocity (MV) of 2370 fps and muzzle energy (ME) of 5100 ft. lbs. Modern A-Square loads for the .416 Rigby drive their 400 grain Monolithic Solid or expanding Dead Tough and Lion Load bullets at a MV of 2400 fps with ME of 5115 ft. lbs. Federal and Norma also offer .416 Rigby factory loads with 400 grain bullets at similar velocities.
Because of its huge case, which is considerably fatter than a .375 H&H Magnum case, there are few rifles adaptable to the .416 Rigby. Remington rectified the problem in 1988 by introducing the .416 Remington Magnum. This cartridge is based on the 8mm Remington Magnum belted case necked-up to accept .416" diameter bullets. This case is smaller than the .416 Rigby case and has the advantage of a standard magnum head size. Ballistic performance is identical to the larger Rigby cartridge because the Remington .416 is loaded to a maximum average pressure of 54,000 cup. Remington factory loads drive a 400 grain bullet at a MV of 2400 fps and ME of 5115 ft. lbs.
As can be seen from the above, the .416 Rigby and .416 Remington Magnum are ballistically identical. Both drive the same weight bullets to the same velocity. And both are world hunting cartridges. In the U.S. CZ, Dakota, and Ruger rifles are available in .416 Rigby. Blaser, Dakota, Remington, Ruger, Sako, Weatherby, and Winchester rifles are available in .416 Rem. Mag.
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 classic British elephant rifle cartridges such as the .450 Nitro Express and .470 Nitro Express in a cartridge that would work in standard (.30-06) length bolt action rifles. The .458 Winchester Magnum has become the world's most popular dangerous thick-skinned game cartridge.
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 to 2040 fps. Federal loads 500 grain solid or controlled expansion bullets at a MV of 2090 fps, which can be taken as typical.
The perspective of this comparison is that of a hunter traveling to Africa from another continent to hunt thick-skinned dangerous game (Cape buffalo, rhino, and elephant). Our hunter wants a "heavy" rifle suitable for the purpose and legal in all jurisdictions. He or she is not looking for a "stopper" per se (stopping frenzied charges at close range is the professional hunter's specialty) but rather a heavy rifle with adequate killing power for normal purposes. In North America, and presumably most of the rest of the world, the choice is most likely to come down to a bolt action rifle in either .416 or .458 caliber.
While the most common (and almost the only) factory loads for the .416 Rigby and Remington calibers drive 400 grain bullets at a MV of approximately 2400 fps, that is not the case with the .458 Win. Mag. The .458 Winchester is factory loaded with several different bullet weights, including 350, 400, 450, 465, 500, and 510 grains at various velocities. Clearly, not all of these will be equally useful for shooting thick-skinned dangerous game. For the handloader, 350 grain .416" and 300 grain .458" bullets are also reasonably common.
So, let's start by comparing the sectional density (SD) of typical .416 and .458 bullets. 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, which is always at a premium when hunting thick-skinned dangerous game. The higher the sectional density figure the better the penetration, all other factors being equal. Anything over .300 is generally pretty good. For comparison, the SD of a 300 grain bullet for the .375 H&H Magnum is .305. Here are some typical SD numbers for .416" and .458" bullets.
The sectional density of the 400 grain .416 bullet and the 500 grain .458 bullet are really exceptional. The 465 grain .458 bullet is good, and will suffice for the heaviest game, including elephant. The 450 grain .458 bullet is equal to the 300 grain .375 bullet, and that has been pronounced fit for dangerous game, but the 450 grain .458 bullet is right at the line. The 350 grain .416 and 350 and 400 grain .458 bullets have SD's recommended for elk and moose (CXP3 class game), which are not thick-skinned game. And the 300 grain .458 bullet has a SD generally regarded as suitable for antelope, deer, and black bear (CXP2 class game).
Of course, bullet expansion has a major influence on penetration, but when using solid (non-expanding) bullets, it can be disregarded. 350 to 400 grain .458 expanding bullets may be an excellent choice for leopard, lion, or the great bears, but they are not the best choice for shooting dangerous thick-skinned game. For the purposes of our comparison we will stick with the 400 grain .416 bullet and the .465 and 500 grain .458 bullets.
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 a .416" bullet is .1359 sq. in.; the frontal area of a .458" bullet is .1647 sq. in.
Next, let's look at velocity. As we have already seen, .416 factory loads drive a 400 grain bullet to higher velocity than the .458 Win. Mag. drives its 500 grain bullet. To recap, the following factory loaded muzzle velocities are typical.
Velocity has a big impact on energy, which has a lot to do with killing power. The following are the muzzle and 100 yard energies for the factory loads compared above.
Trajectory is not usually of primary importance with big bore calibers, but not all game is shot right off the muzzle, either. The best distance at which to shoot dangerous game is said to be between 50 and 150 yards. Here are the approximate trajectories of our three selected loads, calculated for a line of sight 1.5" over the bore (as with a low mounted scope).
The .416's shoot flatter over 200 yards. According to the "Rifle Trajectory Table" they have a 20-25 yard advantage over the .458 Win. Mag. in maximum point blank range (MPBR).
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.
The A-Square handloading and rifle manual Any Shot You Want devotes a lot of space to discussing and evaluating dangerous game loads. Included is an interesting little table for various big game cartridges that quantifies what the author, Arthur Alphin, calls "Penetration Index" and "Shock Power Index."
The Penetration Index (PI) is calculated by dividing kinetic energy with bullet cross sectional area and multiplying the result by the sectional density, and assumes a solid (non-expanding) bullet. The Shock Power Index (SPI) is calculated by multiplying the energy by the frontal area of the bullet. The higher the number the better in both indexes. How valid these numbers are I cannot say, but here are the results.
The .416 has the deepest penetration, and the .458 is a better stopper. I have no idea what it means, but out of curiosity I averaged the PI and SPI numbers for each load and got the following result: 400.5 for the .416/400 load, 467.5 for the .458/465 load, and 428 for the .458/500 load. Does this mean that the .458 with a 465 grain bullet at 2220 fps has the best blend of penetration and shocking power? I don't know, but I would not be surprised if did.
Another indication of killing power is the "Optimal Game Weight Formula" developed by Edward A. Matunas. I figured the maximum optimal game weight for short ranges and got the following results for 50 and 100 yards.
These figures also slightly favor the .458 with a 465 grain bullet. They show that any of these cartridges should flatten any buffalo, but are definitely below optimum for shooting a 13,000 pound African elephant! This may well be true, but I suspect that the Optimum Game Weight Formula is more reliable for game in the 100-1000 pound range than it is for pachyderms.
The final factor to consider when choosing any hunting rifle is recoil. And recoil is certainly a factor when considering big bore dangerous game rifles. Any shooter who isn't up to enduring punishing recoil should not consider hunting with any of these cartridges. It is wise to know one's limits, because the last thing you want to do is flinch off a shot and wound a dangerous game animal. Your professional hunter is not going to thank you if he has to flush a wounded buffalo out of thick brush, and that is assuming you both survive the experience. As always, bullet placement is paramount, and a solid hit in a vital spot with a .338 Win. Mag. is far better than a gut shot with a .458 Win. Mag.
The "Rifle Recoil Table" shows the following recoil figures for 10 pound rifles chambered for the .416 Rem. Mag., .416 Rigby, and .458 Win. Mag.
With about 4 ft. lbs. less recoil, the .416 Rem. Mag. will be a little more pleasant to shoot than the .458 Win. Mag., but unfortunately it isn't enough difference to be decisive for most shooters. The .416 Rigby kicks about like the .458 Mag. because its larger case requires more powder than the .416 Remington to attain the same velocity. Basically, anyone who chooses a .416 over a .458 hoping it kicks less is probably going to be disappointed. Jack O'Connor described the recoil of his .416 Rigby as "tolerable," but he was a much more experienced rifleman than us common folk.
It is not necessary to practice with full power loads all of the time. Here are recoil figures for some "starter" loads taken from the Speer and Hornady Reloading Manuals. Again, recoil has been computed for a rifle weight of 10 pounds.
The .458 Win. Mag. has the smallest case capacity and the biggest bullet selection, so it follows that it has the greatest diversity of reloads. According to the Hornady Handbook, Fifth Edition the 300 grain JHP .45-70 bullet can be driven at MV's from 1850 fps to 2200 fps at considerably less recoil than any of the other elephant rifle cartridges. Such loads, by the way, are deadly on all CXP2 class game. The intermediate .458 load driving a 350 grain bullet at a MV of 2100 fps is sufficient for all North American big game, as is either of the .416 reduced power loads. The .458 Win. Mag. does seem to be the standout for use on North American game with reduced power loads and for low power practice loads.
Ammunition availability is always an important consideration for any rifle that may be used far from home, and while all three calibers under consideration are worldwide big game calibers, in this area the .458 Winchester Magnum stands alone. .458 ammunition is both more economical (not that any of these cartridges are cheap) and more available than any other elephant cartridge. Ditto for bullets and other reloading supplies. The .416 Rigby is the most expensive of the three cartridges for which to purchase ammunition and brass.
There are also more models of rifles chambered for the .458 Win. Mag. As it fits standard length magnum actions, which are common, many manufacturers can and do chamber for the .458 Magnum. The .416 Remington Magnum requires a long magnum action, so only rifles long enough for the .375 H&H cartridge can be adapted to it. And the .416 Rigby is both long and fat with an oversize rim diameter; it requires a special action even bigger than a .375 H&H or .416 Remington action. Naturally, the larger the action the scarcer and more expensive it tends to be.
To recap what we have learned, the 400 grain .416 bullet has a higher SD than the 465 grain .458 bullet, and the 500 grain .458 bullet is even better. All three of these bullets offer good penetration, and the .416/400 grain load probably has the best penetration of all.
In terms of kinetic energy, the .416/400 grain bullet and the .458/465 grain bullet are pretty much equal; the .458/500 grain bullet trails the other two by an average of 273.5 ft. lbs. at 100 yards. This is a noticeable but probably not critical difference.
In bullet frontal area, the .458 bullet clearly has the advantage regardless of weight, and the .458/465 load is probably the best "stopper" of the three, although not dramatically superior to the other two loads.
In trajectory the two .416's have an advantage over the .458 Win. Mag. They shoot flatter by 0.6" to 1.6" over 200 yards and have a 20-25 yard advantage in maximum point blank range.
Although it is hard to quantify, the A-Square .458 factory load with a 465 grain bullet may have some advantage in killing power. We know from experience that with full power loads the .416 Rem. Mag., .416 Rigby, and .458 Win. Mag. are all adequate for thick-skinned dangerous African game.
Just as there is no dominant load in terms of ballistics, there is also no real winner in terms of recoil, although with factory loads the .416 Remington Magnum kicks slightly less than the .416 Rigby and .458 Win. Mag. It would be fair to say that all three cartridges kick like the devil with full power loads. However, for the reloader, the .458 Winchester Magnum seems like the best candidate for reduced power practice and North American big game loads. The reloader can assemble reasonable loads for everything from whitetail deer to brown bear and moose at considerable savings in both cost and recoil.
Copyright 2003, 2012 by Chuck Hawks. All rights reserved.