Compared: The .264 Winchester Magnum and .270 Weatherby Magnum
By Chuck Hawks
The .264 Winchester Magnum and .270 Weatherby Magnum are another interesting comparison. Both are ultra long range big game hunting cartridges. The .264 Win. Mag. 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 older .270 Weatherby Magnum was created in essentially the same way and designed to accept standard .270 caliber (.277" diameter) bullets. The .270 Wby. has a slightly longer maximum case length (2.549" compared to 2.50") and the .264 Mag. has a slightly longer overall cartridge length (3.340" compared to 3.295") and uses a slightly smaller diameter bullet. Both are designed for use in rifles with standard (.30-06) length actions.
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 the .264 and .270 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 novice, inexperienced, or occasional shooters.
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, although the Featherweight comes with a 24" barrel. 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. Current .264 factory loads using 140 grain bullets have been reduced in velocity to 3030 fps and are measured in a 24" barrel. The MAP of the .264 Magnum is pegged at 53,000 CUP.
The .270 Weatherby Magnum
The .270 Weatherby Magnum is the original Weatherby Magnum, dating back to 1943. It was the first cartridge introduced by Roy Weatherby and many users would say it is still the best. It is the lightest kicking Weatherby caliber with all-around (CXP2 and CXP3) game getting capability. It is a standard (.30-06) length cartridge based on a shortened, blown-out and necked-down .300 H&H belted case given a Weatherby double radius shoulder. The bore diameter is .270" and the bullet diameter is .277", the same as the .270 Winchester.
Reloaders can use any standard .277" diameter bullet, generally ranging from 90-160 grains. The eight Weatherby factory loads currently offered come with bullets weighing 110, 130, 140 and 150 grains. Federal Premium offers a single .270 Weatherby factory load using a 130 grain Trophy Bonded Tip bullet at 3200 fps. Hornady, Remington and Winchester do not offer .270 Wby. Mag. factory loads.
Reloaders have a wide variety of bullet weights from which to choose. Depending on manufacturer, these typically include 90, 100, 110, 130, 140, 150 and 160 grains.
Weatherby .270 Magnum rifles come with a 26" barrel and Weatherby factory load ballistics are derived in a 26" test barrel. The SAAMI maximum average pressure (MAP) for the .270 Weatherby is 62,500 piezo psi.
The .264 and .270 Magnums are long range, all-around cartridges. For the purposes of this comparison, we will stick with representative factory loads. These cartridges are probably at their best and most versatile with relatively heavy for caliber bullets, meaning 140 grains in the .264 and 150 grains in the .270, so those are the bullet weights we will compare. Remington offers a single factory load using a 140 grain Core-Lokt bullet (BC .384) at a MV of 3030 fps. In .270 Mag., Weatherby offers a factory load using the 150 grain Hornady Spire Point InterLock bullet (BC .462), so that is the load we will use to represent the .270 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 and Weatherby 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 .270 Mag. starts 215 fps faster and its bullet has a higher BC that retains velocity better down range. In our comparison factory loads the .270 Wby. Mag. has a clear 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. Energy is a good indication of the power of similar rifle cartridges. 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 higher velocity, it was a foregone conclusion that the .270 Wby. would develop more energy at all ranges.
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 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. The .270 Magnum has the advantage of 1.26 inches less drop at 300 yards and 4" less drop at 400 yards.
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.
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 .277" diameter (.270 caliber) bullet is fatter than a .264" diameter bullet. Here are their cross-sectional areas.
The .270 has the advantage in cross-sectional area 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 .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. 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.
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 .270 Mag. has the HITS advantage.
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, the .264 clearly wins the recoil comparison. The .270 Magnum's felt recoil will be significently more unpleasant in an 8.5 pound rifle. 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 .270 Weatherby Magnum has the advantage in velocity, energy, trajectory, bullet cross-sectional area and killing power. The .264 Winchester Magnum has the advantage in sectional density and lower recoil.
Neither cartridge is available in many rifle brands. The .264 Magnum is primarily available in Winchester Model 70 rifles and the .270 Magnum is primarily available in Weatherby Mark V rifles.
Only Remington and Winchester load .264 ammunition and only a single load using a 140 grain bullet is offered by each. Federal offers a single .270 Wby. factory load using a 130 grain bullet, while Weatherby offers eight factory loads using four different bullet weights for their Magnum. If you do not reload you own ammo, the .270 Wby. Mag. offers more choices in factory loaded ammunition, but neither is particularly widely distributed.
Both the .264 and .270 Magnums are capable of taking all Class 2 big game within their maximum point blank range 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.
Copyright 2013 by Chuck Hawks. All rights reserved.