Compared: The .264 Winchester Magnum and .270 Winchester
By Chuck Hawks
The .270 Winchester, based on a necked-down .30-06 case, is the classic North American long range hunting cartridge. It was introduced in 1925 and for many years it was the highest velocity, factory loaded, big game hunting cartridge. The .270 became popular worldwide and today it will be found everywhere big game is hunted. It is also one of the few best selling hunting cartridges that was not originally designed for military use; neither was it adapted from a match cartridge. The .270 is strictly a civilian hunting cartridge, optimized for that purpose without compromise.
There is a plethora of .270 (actually .277" diameter) bullets available to reloaders and practically every ammo maker who reloads centerfire hunting ammunition offers loads in .270 Winchester. For big game hunting, the popular bullet weights are 130 grains, 140 grains and 150 grains.
The .264 Winchester Magnum, based on a .30-06 length belted magnum case, was Winchester's first attempt to supersede the .270. It was introduced in 1958 and remains the fastest, flattest shooting of all commercial 6.5mm cartridges. The .264 Mag. has never rivaled the commercial success of the earlier .270, but it has sold well enough to keep rifles and ammunition in production all these years and, given the recent interest in 6.5mm (.264) cartridges in North America, its popularity may grow. Like the .270, the .264 Win. Mag. was designed from the outset as a long range hunting cartridge. Among the major US ammo makers, Remington and Winchester offer factory loads in .264 Win. Mag. and both use 140 grain bullets exclusively. The .270 and .264 make an interesting comparison, so let's get to it.
The .270 and the .264 are long range, all-around cartridges and it happens that the optimum factory loads for the purpose in both calibers use bullets weighing 140 grains, so that is the bullet weight we will compare. In .270, Remington offers a factory load using their 140 grain Core-Lokt Ultra Bonded bullet (BC .360) at a MV of 2925 fps and in .264 Big Green offers a similar 140 grain Core-Lokt bullet (BC .384) at a MV of 3030 fps. These are both flat base spitzer bullets of similar form and make a fair comparison.
We will compare these two cartridges in velocity, kinetic energy, trajectory, sectional density, 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 CXP2 and CXP3 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 140 grain bullets at the muzzle, 100, 200, 300 and 400 yards when fired in 24" barrels.
The .264 starts a little faster and its sleek 6.5mm bullet retains that velocity a little better as the range increases. When they introduced the .264 Magnum, Winchester stated that its advantage over the .270 would only become apparent at ranges in excess of 300, or possibly 400, yards.
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, with the .270 being somewhat marginal at that distance and the .264 providing a little insurance in the form of extra energy.
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.
Clearly, these are both flat shooting cartridges and, while the .264 has the advantage of a flatter trajectory at all ranges, the difference is not great. Another way to compare the trajectory of cartridges and loads is by their maximum point blank range (+/- 3"). The MPBR of the .270/140 is about 292 yards and the MPBR of the .264/140 is approximately 300 yards.
Sectional Density (SD) 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, it is apparent that the .264 should be the deeper penetrating bullet in extreme circumstances, creating a longer wound channel.
Bullet Cross-Sectional Area
Frontal (cross-sectional) area plays a significant role in killing power. Clearly, the bigger the hole you punch in an animal, the greater the potential damage. The length and diameter of the wound channel are the critical factors in killing power. Obviously, a .277" diameter (.270 caliber) bullet is fatter than a .264" diameter (6.5mm caliber) bullet and, other factors being equal, will punch a bigger hole. The frontal area of a .264" bullet is .0547 square inches. The frontal area of a .277" bullet is .0603 square inches. The .270 has the advantage in frontal area with all bullet weights and should generally produce a wider wound cavity.
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 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 .277" 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 (extreme velocity, heavy weight bullets, "KO" value, etc.). 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 calculated for a range of 100 yards, a typical distance for shooting large game. Here are the approximate HITS scores for our comparison loads.
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, but the .264 maintains a modest advantage in HITS killing power.
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.
Change the rifle weight to 8.0 pounds and the figures look like this:
As you can see, rifle weight is very important in terms of actual recoil and in 8.0 or 8.5 pound rifles both cartridges are below the 20 ft. lb. "do not exceed" level. Choosing medium weight (or heavier) rifles for these cartridges is a pious idea, for either becomes a nasty kicker in a lightweight rifle. Nor are short barrels recommended, for both velocity loss and muzzle blast are significant in barrels shorter than 24".
The biggest difference between the .270 Winchester and the .264 Win. Mag. is not in ballistics or killing power, but in the availability of rifles and ammunition. In this area, the .270 has a big advantage. Almost every manufacturer who builds a rifle that can handle the .270 chambers for it. The selection is broad and includes all types of rifles including bolt, lever, pump, autoloading, single shot and double barrel designs. In Europe, even drillings (three barrel rifle/shotgun combinations) are chambered for the .270 Winchester. Only a select few rifles are offered in .264 Mag. The situation is much the same in factory loaded ammunition and selection of factory loaded bullet weights, with the .270 totally dominating the .264 Mag. in terms of choices. Particularly if you do not reload you own ammo, the .270 is the better cartridge.
As we saw in the section on killing power, both the .270 and .264 are capable of taking all CXP2 class 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, goats, sheep and feral hogs. Even very large examples of these creatures seldom exceed 300 pounds on the hoof. In addition, either caliber is a reasonable choice for CXP3 class game, such as elk, out to beyond 100 yards. Both calibers have been used with great success on thin-skinned plains game in Africa, where the .270, in particular, is regarded as a classic plains game cartridge.
I am convinced that it is a balance of flat trajectory, good killing power and tolerable recoil that is the secret behind the .270 Winchester's commercial success. The .264 Winchester Magnum offers a similar blend of advantages, including somewhat flatter trajectory, at the price of increased recoil, muzzle blast, and decreased barrel life. It is a slightly better long range cartridge and it kills as well or better than the .270 Winchester.
Copyright 2010, 2012 by Chuck Hawks. All rights reserved.