Compared: The .264 Winchester Magnum and 7mm Remington Magnum
By Chuck Hawks
The .264 Winchester Magnum and 7mm Remington Magnum make an interesting comparison. The .264 case was created by shortening a .300 H&H Magnum case to fit in a .30-06 length action, blowing it out to a sharp shouldered shape and necking it down to accept standard 6.5mm (.264" diameter) bullets. The 7mm Remington Magnum is essentially a .264 Mag. case necked-up (or a .338 Win. Mag. case necked-down) to accept standard 7mm (.284" diameter) bullets. The two cases share the same .532" rim and belt diameter, .513" head diameter, 2.040 body length, 25-degree shoulder angle and 2.50" case length. The .264 Mag. has a slightly longer overall cartridge length (3.340" compared to 3.290") and uses a slightly smaller diameter bullet, but seen side by side it is hard to tell the two cartridges apart.
The two cartridges compete for a share of the same all-around and long range, big game cartridge market. In rifles of typical magnum weight (about 8.5 pounds), the .264 and 7mm Magnums kick about as hard as a .30-06, which means that they are within the reach of most experienced shooters. They are, however, not appropriate cartridges for inexperienced shooters or once a year deer hunters.
The .264 Winchester Magnum
The .264 Win. Mag. was designed from the outset as a long range hunting cartridge. It was introduced in 1958 and remains one of our flattest shooting commercial cartridges. Winchester and Remington initially offered 100 grain and 140 grain bullet weights in the .264, but only the 140 grain load survives today.
Among the major US ammo makers only Remington and Winchester offer factory loads in .264 Win. Mag. 140 grains is the all-around bullet weight for 6.5mm cartridges, but reloaders have other options. Common .264" bullet weights include 90, 95, 100, 120, 123-125, 129-130, 140 and 156-160 grains. Generally speaking, hunting bullets lighter than 120 grains are intended for varmints and other small animals and 120 grain and heavier bullets are intended for medium or large game.
The .264 Win. Mag. was designed for use in rifles with 26" barrels. It was first offered in the Winchester Model 70 Westerner rifle, which was supplied with a 26" barrel and most Model 70 .264 Mag. rifles are still supplied with 26" barrels. For many years, Winchester and Remington .264 factory ballistics were measured in 26" barrels and called for a 140 grain bullet at a muzzle velocity (MV) of 3200 fps. Unfortunately, current .264 factory loads using 140 grain bullets have been reduced in velocity to 3030 fps from a 24" barrel.
The .264 Mag. has never rivaled the commercial success of the later 7mm Remington Magnum. However, it has sold well enough to keep rifles and ammunition in production all these years and, given the recent increased interest in 6.5mm (.264") cartridges in North America, its popularity may grow.
The 7mm Remington Magnum
Remington introduced their 7mm Magnum cartridge in 1962. Earlier standard length 7mm Magnums, among them the 7mm Weatherby Magnum, are similar in concept and performance, but it is the 7mm Rem. Mag. that caught the attention of the shooting public. It was the right cartridge at the right time. Commercial success was immediate for the 7mm Rem. Mag. and continues to this day, as it is the best selling of all centerfire magnum rifle cartridges.
The 7mm Remington Magnum has proven excellent for use on Class 2 and Class 3 game, particularly at long range. The popular saying that the 7mm Magnum shoots as flat as a .270 and hits as hard as a .30-06 is not far off the mark.
All major ammunition companies load the 7mm Rem. Mag. cartridge. Remington currently offers 10 factory loads for their 7mm Magnum, loaded with bullets weighing 140, 150 and 160 grains. 150 grains seem to be about the optimum all-around bullet weight for any 7mm Magnum rifle, but reloaders have a wide variety of bullet weights from which to choose. Depending on manufacturer, these typically include 110, 115, 120, 130, 139-140, 145, 150-154, 160-162 and 175 grains.
The .264 and 7mm Magnums are long range, all-around cartridges and it happens that common factory loads for the purpose in both calibers use bullets weighing 140-150 grains, so those are the bullet weights we will compare. The factory load ballistics for the .264 Winchester and 7mm Remington Magnums are currently measured in 24" test barrels. In .264 Mag., Remington offers a single factory load using a 140 grain Core-Lokt bullet (BC .384) at a MV of 3030 fps. In 7mm Mag., Remington offers their sleek 150 grain AccuTip boat-tail bullet (BC .530) at a MV of 3110 fps and that is the load that we will use to represent the 7mm Magnum.
We will compare these two cartridges in velocity, kinetic energy, trajectory, sectional density (SD), bullet frontal area, killing power and recoil. We will conclude with a few comments about the availability of rifles and ammunition and the suitability of these calibers for their intended purpose of hunting Class 2 and Class 3 big game.
Velocity matters because it flattens trajectory and a cartridge that shoots flatter is easier to hit with at long range. It is the major component of kinetic energy. Velocity and energy figures at various ranges are published by Remington for their factory loaded ammunition. Here are the velocity (in feet per second) figures for our selected bullets at the muzzle, 100, 200, 300 and 400 yards.
The 7mm Mag. starts 80 fps faster and its sleek plastic tipped, boat-tail bullet with a higher BC retains that velocity better as the range increases. Reloaders can load both cartridges with tipped, boat-tail bullets, but in our comparison factory loads the 7mm Rem. Mag. has the velocity advantage.
Kinetic energy is important because it is a measure of the amount of work (i.e. destruction) of which each cartridge is capable. Energy powers such important functions as bullet expansion, penetration and tissue destruction. Following are the published energy figures in foot-pounds for our selected loads at 100, 200, 300 and 400 yards.
It is sometimes generalized that a good elk bullet needs to impact with at least 1200 ft. lbs. of energy. If so, these are both 400 yard elk cartridges. However, given its heavier bullet and somewhat higher velocity, it was a foregone conclusion that the 7mm Mag. would carry more energy at all ranges than the .264 Mag.
Trajectory matters because a cartridge that shoots flatter is easier to hit with at long range and bullet placement is the most important factor in humanely harvesting big game animals. Here are Remington's published trajectory figures for our two loads at 100, 200, 300 and 400 yards, based on a 200 yard zero with scoped rifles with the line of sight 1.5" above the center of the bore.
These are both flat shooting cartridges and, while the 7mm has the advantage of 3.2 inches less drop at 400 yards, the difference is only one inch at 300 yards, which is about the maximum point blank range (MPBR) of both cartridges and loads.
Sectional Density is essentially the ratio of a bullet's weight to its diameter. SD is an important factor in penetration, because a long slender bullet of a given weight penetrates better than a short fat bullet of the same weight, other factors being equal. The higher the SD, the better the potential penetration. Here are the SD figures for our selected bullet weights in both calibers.
Sectional densities in the .250 range are generally regarded as suitable for hunting CXP3 game, so both of these bullets have the potential for adequate penetration on large animals. However, the .264/140 has the advantage in SD and, other factors being equal, should be the deeper penetrating bullet, potentially creating a longer wound channel.
Bullet Cross-Sectional Area
Cross-sectional area plays a significant role in killing power. The bigger the hole you punch in an animal, the greater the potential damage. Obviously, a .284" diameter (7mm caliber) bullet is fatter than a .264" diameter (6.5mm caliber) bullet. Here are their cross-sectional areas.
The 7mm has the advantage in cross-sectional area with all bullet weights and, potentially, can produce a wider wound cavity. Both sectional density and cross-sectional area directly influence the extent of the wound cavity in a game animal. In terms of wound cavity volume, an advantage in SD tends to compensate for a disadvantage in cross-sectional area and vice-versa.
Killing power is the most difficult factor to quantify. Bullet placement is by far the most important factor in a cartridge's effectiveness on game and that is a function of the hunter's judgment and skill, not the cartridge used. The construction and performance of a hunting bullet is also very important and practically every type of hunting bullet is available (at least to reloaders) in both .264" and .284" diameter. Kinetic energy is one indication of potential killing power, as are bullet frontal area and sectional density, but none of these tells the entire story.
There are many ways to estimate the killing power of big game cartridges. Some seem to correlate with observed results in the field and some are simply concocted to promote the author's point of view. One of the newer, and better, methods of estimating killing power is the "Hornady Index of Terminal Standards" (HITS), which includes factors such as bullet weight, sectional density, ballistic coefficient and impact velocity. HITS are normally calculated for a range of 100 yards, a typical distance for shooting large game. Here are the approximate HITS scores for our comparison loads.
As you can see, there is little difference in killing power. A HITS rating of 901-1500 is considered adequate for large game, such as North American elk and African kudu. Both cartridges are clearly adequate for killing large game at ranges in excess of 100 yards.
Recoil is an important factor, because anyone can shoot better with a gun that kicks less. Remember that shot placement is, by far, the most important factor in killing power, so differences in recoil matter. Guns that kick less are more fun to shoot and generally get used more. Here are recoil energy (in foot-pounds) and velocity (in feet per second) figures for our selected loads when fired in 8.5 pound rifles.
As you can see, both cartridges are below the 20 ft. lb. "do not exceed" level. However, the .264 clearly wins the recoil comparison. Choosing medium weight (or heavier) rifles for these cartridges is a pious idea, for either becomes a nasty kicker in a lightweight rifle and the muzzle blast is intimidating in barrels shorter than 24 inches.
The 7mm Remington Magnum has the advantage in velocity, energy and bullet cross-sectional area. The .264 Winchester Magnum has the advantage in sectional density and recoil. The 7mm Magnum's advantage in trajectory is slight out to 300 yards, which is about the MPBR of both cartridges. The two cartridges and loads are similar in HITS killing power at 100 yards.
The biggest difference between the 7mm Rem Mag. and the .264 Win. Mag. is not in ballistics or killing power, but in the availability of rifles and ammunition. In this area, the 7mm Magnum has a big advantage. Almost every manufacturer who builds a rifle that can handle belted magnum cartridges chambers for it and all major ammunition manufacturers turn out 7mm Rem. Mag. factory loads with a variety of bullet weights.
Only a select few rifles are offered in .264 Magnum and only Remington and Winchester load the ammunition. 140 grains is the only bullet weight available from either manufacturer. If you do not reload you own ammo, the 7mm Rem. Mag. offers substantially more choices in factory loaded ammunition.
Both the .264 and 7mm Magnums are capable of taking all Class 2 big game within their maximum point blank range of approximately 300 yards with our selected loads. In North America that includes such animals as pronghorn antelope, the various deer species, black bear, caribou, goats, sheep and feral hogs. In addition, either caliber is a reasonable choice for Class 3 class game, such as elk, at reasonable ranges. Likewise, both calibers have been used with success on thin-skinned plains game in Africa. In practice, their capability as big game hunting cartridges is similar.
Copyright 2013 by Chuck Hawks. All rights reserved.