The 7mm Remington Magnum
By Chuck Hawks
Illustration courtesy of Hornady Mfg. Co.
Remington introduced their 7mm Magnum in 1962. The case was created by simply necking down the .338 Winchester Magnum case (or necking up the .264 Win. Mag. case, since they are the same) to accept .284" bullets. Remington was not the first to do this, since the 7mm Weatherby Magnum had been around for well over a decade, as had several wildcat 7mm Magnums including the well regarded 7mm Sharpe & Hart. However, a new cartridge from a major manufacturer is always bigger news than a wildcat or proprietary round.
The 7mm Rem. Mag. was an immediate success, probably because it provided magnum lovers with a genuine all-around cartridge that was less punishing to shoot than the .300 Magnums. The recoil energy generated by shooting a 150 grain bullet at 3100 fps in an 8.5 pound 7mm Rem. Mag. rifle is 19.8 ft. lbs. according to the "Rifle Recoil Table." This is very similar to the recoil of the typical 8 pound .30-06 rifle shooting the same weight bullet. In fact, given the fact that magnum rifles are generaly about a half pound heavier than rifles for standard calibers like the .30-06, the recoil energy of a 7mm Magnum is very comparable to that of a .30-06 with all bullet weights. And, of course, the 7mm Magnum out ranges the .30-06 in terms of both trajectory and killing power. In addition, barrel life is reported to be longer than with the .264 Winchester Magnum, .270 Weatherby Magnum, and some of the other very high velocity small bore calibers, which have drawn criticism in this regard.
The 7mm Rem. Mag. quickly became the best selling of all the magnum calibers, number seven overall on the ammunition sales lists, and it remains so today. I don't think it is a secret that there are only three magnum calibers that are chambered in a wide variety of rifles; these are the 7mm Rem., .300 Win., and .338 Win. Of these three the 7mm Magnum is, by a considerable margin, the most pleasant to shoot.
The Remington 7mm Magnum is generally regarded as suitable for all thin-skinned game world wide, although (like the .30-06) it is marginal on game above the 600 pound class. It has been successfully used on dangerous game like leopard, jaguar, lion, tiger, and the great bears at safe ranges. It is not, however, the best choice for stopping a charge at close range. Leave that to the powerful medium and large bore rifles.
Ammunition for the 7mm Rem. Mag. is manufactured not only in North America, but also in Australia, Europe, Africa, and possibly other places. It is very widely distributed, and can be purchased in most countries where big game is hunted. The original factory loads for the 7mm Rem. Mag. were (and are) a 150 grain spitzer bullet at a MV of 3,110 fps and a ME of 3,221 ft. lbs., and a 175 grain spitzer bullet at a MV of 2,860 fps and ME of 3,178 ft. lbs. Remaining energy at 300 yards with the 150 grain bullet is 1,792 ft. lbs.; with the 175 grain bullet it is 1,956 ft. lbs.
In addition, factory loads with 139-140 grain bullets at 3,150 fps, a 154 grain bullet at 3035 fps, 160-162 grain bullets at 2,940 fps, a 165 grain bullet at 2,900 fps, and 170 grain bullets at 3018 fps have been added. This is a pretty good selection of factory loads for big game hunting. The SAAMI pressure limit for the Big 7 is 52,000 cup.
Because of the high velocity of the 7mm Remington Magnum, the 139-140 grain bullets (SD .248) are best used on medium size game like pronghorn antelope, impala, and the various deer species. The 150 grain (SD .266) to 160 grain (SD .283) spitzer bullets make excellent general purpose big game bullets for the 7mm Mag. The heavy 175 grain bullets (SD .310) are generally designed for deep penetration on big or dangerous animals like moose and the great bears. The 7mm Magnum has been widely used for Alaskan game, and for all of the African plains game.
The trajectory of 7mm Rem. Mag. factory loads with 175 grain bullets is similar to that of the .270 Winchester with a 150 grain bullet; with 150 grain bullets the 7mm Magnum's trajectory is about like a .270 with a 130 grain bullet. In other words, it shoots just as flat as a .270 Winchester and hits even harder (at both ends, of course).
If a scoped 7mm Mag. rifle is zeroed to put a 150 grain Nosler Partition bullet at a MV of 3,110 fps 2.5 inches high at 100 yards, it will hit approximately 3 inches high at 150 yards, 2.3 inches high at 200 yards, and 3 inches low at 305 yards. In other words, that load has a maximum point blank range of 305 yards (+/- 3").
Reloading for the 7mm Rem. Mag. can both save money and allow the shooter to develop accuracy loads for his particular rifle, which the big loading companies obviously cannot do. Reduced loads for practice or to reduce blast and recoil are also possible. Naturally, the slower burning powders, starting at about the burn rate of IMR 4350, are best in this big case with all bullet weights from 120 grains on up. IMR 4831 and H4831 are widely recommended powders for most big game hunting applications.
The fifth edition of the Nosler Reloading Guide reported that IMR 4831 was the most accurate powder with their 150 grain bullets. 61.0 grains of IMR 4831 behind a 150 grain bullet gave a MV of 3020 fps, and 65.0 grains of the same powder gave a MV of 3240 fps. These loads used Winchester cases and Federal 215 primers and were chronographed in a 24" barrel.
The reloader has access to some light bullets that are not factory loaded, such as the 100, 115, and 120 grain bullets intended for small animals or varmints. But the Big 7 is not a good choice for that sort of shooting, and lightly constructed bullets may not withstand the very high velocities at which they can be driven. Barnes offers their 195 grain Original bullet for those wanting something super heavy, and it can be driven at well over 2,600 fps--with some loads to nearly 2,700 fps.