Compared: The .257 Weatherby Magnum and .264 Winchester Magnum
By Chuck Hawks
This pair of ultra-long range, magnum cartridges represents the apex of (respectively) Weatherby and Winchester design. The .257 was designer Roy Weatherby's favorite CXP2 game cartridge (he also used it on CXP3 game) and the .264 is Olin/Winchester's attempt to best the performance of their own .270 Winchester (the benchmark for long range hunting cartridges) beyond 400 yards.
These were conceived primarily as long range deer, antelope, goat and sheep cartridges. Both have proven adequate for 500-600 pound CXP3 game such as Rocky Mountain elk, although the .264, with its heavier bullets of greater sectional density (SD), clearly has the advantage for use on large game and as an "all-around" (CXP2 and CXP3 game) cartridge.
The .257 Weatherby Magnum
This is one of Roy Weatherby's original cartridges. It is based on a blown-out, shortened and necked-down .300 H&H Magnum case. It uses the standard belted magnum .532" rim and case head diameter and may be chambered in any rifle suitable for .30-06 length belted magnums (7mm Rem. Mag., .300 Win. Mag., etc.) The .257 has become the second most popular Weatherby cartridge (after the .300 Wby. Mag.) and is now offered by a number of rifle and ammunition manufacturers besides Weatherby.
Among its virtues are very flat trajectory, good killing power and tolerable recoil. Unlike most Weatherby Magnum cartridges, the .257 Mag. is within the recoil tolerance of most shooters when fired in a reasonably heavy rifle such as a Weatherby Mark V Deluxe or Vanguard Deluxe. In other words, it shoots as flat as a .300 and, unlike the bigger Weatherby calibers, won't kick your head off. The .257 is the natural choice for those wanting a Weatherby Magnum rifle without the outsized recoil and I am convinced that is the reason for its popularity.
Seven Weatherby .257 factory loads are available with bullets from 87 grains (at 3825 fps MV!) to 120 grains (at 3305 fps MV). Weatherby Mark V Magnum rifles come with 26" barrels and their factory ballistics are developed in test barrels of that length. Other bullet weights include 100, 110, 115 and 117 grains. Given its large case capacity and small bore, the heaviest bullets (115 grains plus) make the most sense in a .257 Magnum rifle used for hunting big game. The SAAMI maximum average pressure (MAP) for the .257 Weatherby is 53,500 cup.
The .264 Winchester Magnum
The .264 offers the highest performance of all standardized 6.5mm cartridges, yet it has almost become the forgotten member of Winchester's magnum family. It is still offered in a couple of factory built rifles and ammunition is available from Winchester and Remington (one load from each using a 140 grain bullet at a MV of 3030 fps from a 24" test barrel). To get premium .264 loads, one must patronize specialty ammunition companies such as Stars & Stripes or reload your own. Stars & Stripes offers a Production .264 Mag. load that drives a Barnes TSX bullet at a MV of 3154 fps and pretty much whatever you want in Custom loads, as long as it is within SAAMI MAP specifications (53,000 cup).
The .264 Magnum's sluggish sales are due to a North American hunter bias for big game cartridges of .270 caliber or greater, coupled with an unfounded mistrust of 6.5mm "European" cartridges. Fortunately, this is slowly changing (partly due to the efforts of Guns and Shooting Online) as word is getting around that 6.5mm (.264") is actually a superior caliber with a great deal to recommend it. As the cloud of ignorance about 6.5mm cartridges is dispelled among American shooters (Europeans and Africans already know what a useful caliber it is), the .264 Win. Mag. may yet see better days. I understand that the sales of .264 reloading dies are strong, which is always a good sign.
To represent the .257 Weatherby we will use the Weatherby factory load with its 120 grain Nosler Partition bullet at a MV of 3305 fps. To represent the .264 Winchester we will use the Stars & Stripes factory load with a 130 grain Barnes TSX bullet at a MV of 3154 fps. Nosler Partition and Barnes TSX bullets are widely available to reloaders, who can duplicate these ballistics at home. Our comparison loads thus represent both premium factory loads and maximum reloads.
We will compare the .257 Wby. Mag. and .264 Win. Mag. in sectional density and ballistic coefficient, velocity, energy, trajectory, bullet cross-sectional area, killing power and recoil. At the end will be a few concluding comments.
Sectional Density and Ballistic Coefficient
Sectional density is defined as a bullet's weight (in pounds) divided by the square of its diameter (in inches). Other factors being equal, the higher the SD, the deeper a bullet penetrates and thus SD is an important factor in killing power.
Ballistic coefficient is a measurement of how well a bullet flies through the air. The higher the BC, the more aerodynamic the bullet and the lower its drag. A higher BC helps a bullet retain more of its initial velocity and energy down range and results in a flatter trajectory. A flatter trajectory makes hitting easier as the range increases. Here are the sectional densities and published ballistic coefficients for the bullets used in our comparison loads.
The BC of the .257 bullet is good, but the BC of the .264 bullet is very good and presumably will allow it to retain a higher percentage of its initial velocity at long range. The SD's of both bullets are similar and excellent for hunting CXP2 game, where a SD of .225 is considered more than adequate.
Bullet Cross-sectional Area
Bullet weight has no bearing on cross-sectional (frontal) area, only caliber. The cross-sectional area of a hunting bullet is important because, other factors being equal, a fatter bullet makes a wider wound channel and damages more tissue. This translates to quicker and more humane kills. The actual bullet diameter of the .257 Mag. bullet is .257". The bullet diameter of the .264 Mag. bullet is .264". Following are the frontal areas of each in square inches.
Obviously, if bullet expansion percentage and penetration are identical, a .264" bullet will always punch a larger diameter hole than a .257" bullet.
Higher velocity means flatter trajectory, given bullets of equal ballistic coefficient. Velocity is also the most important factor in the formula used to compute kinetic energy. Here are the velocity figures from the muzzle to 500 yards (well beyond the MPBR of both cartridges) in feet-per-second for our selected .257 Wby. Mag. and .264 Win. Mag. loads.
The 6.5x55 bullet starts out about 150 fps slower, but at 300 yards the remaining velocity of the two bullets is identical and beyond that distance the .264 has a velocity advantage.
Kinetic energy is a measure of the bullet's ability to do work and it is widely used to compare the power of rifle cartridges. Energy powers bullet penetration and expansion, which are very important elements in killing power. The key factors in computing kinetic energy are bullet mass and the square of bullet velocity. Here are the energy figures for our selected loads in foot-pounds from the muzzle (ME) to 500 yards.
These figures show that both calibers are adequate for killing CXP2 game at ranges beyond 500 yards. (However, that does not justify shooting at any animal beyond the MPBR of the cartridge.) A load that can deliver a hunting weight bullet carrying over 1200 ft. lbs. is generally considered adequate for the common CXP3 game species and while the .257 Magnum generates sufficient energy, it is considered marginal for such heavy game due to its relatively light, small diameter bullet. The .264 Magnum, on the other hand, can use 140 to 160 grain bullets and with such bullets, it is a recognized CXP3 cartridge.
Trajectory is important to hunters because the flatter a bullet's trajectory, the easier it is to achieve accurate bullet placement at long and unknown ranges. The primary factors influencing trajectory are bullet velocity and ballistic coefficient.
The best way to compare the trajectory of hunting loads is by their maximum point blank range (MPBR). MPBR is the distance at which the bullet drops 3" below the line of sight and represents the longest range at which shots at big game animals should be taken. Here is the MPBR based trajectory of our comparison loads from 100 to 500 yards.
Perusal of these drop figures makes it clear why, as flat shooting as they are, even these ultra-long range cartridges should not be used for shots at big game animals beyond their MPBR and certainly not at 500 yards. As you can see, the .257 shoots slightly flatter than the .264 and has a seven yard advantage in MPBR.
Killing power is the most difficult factor to quantify. Optimum Game Weight (OGW) is a system devised by Edward A. Matunas to express the killing power of rifle cartridges in terms of an animal's live weight and the optimum distance at which it can be taken with a given cartridge and load. Thus, it compares the killing power of different cartridges and loads in a way that is relevant in the field.
To reduce the variables, Matunas started with the assumption that bullet design and placement are adequate for the task. We need not go into the formula itself here, suffice to say that while not perfect, the OGW system does seem to have a higher correlation with reality than most other systems for estimating the killing power of big game rifle cartridges. (For more on OGW, see the "Expanded Optimum Game Weight Table" on the Tables, Charts and Lists page.) The figures below represent optimum game weight in pounds and distance in yards from the muzzle to 500 yards.
These OGW figures largely confirm what was indicated by the bullets' remaining kinetic energy. Both cartridges and loads are adequate for all species of CXP2 game beyond their MPBR. Based on the OGW of our comparison loads, the .257 Weatherby should be an adequate elk cartridge to perhaps 150 yards and the .264 Winchester to at least 200 yards. In terms of OGW killing power, the .264 is the more potent cartridge.
Recoil Energy and Velocity
Recoil is what makes shooting powerful rifles a challenge. Bullet placement is, by far, the most important factor in killing power and rifle recoil is the #1 enemy of accurate bullet placement. A hunter who flinches in anticipation of the rifle's firing is a menace in the field. Here are some approximate recoil energy (in foot pounds) and velocity (in fps) figures for our comparison loads when fired in 9 pound rifles.
These are not cartridges for lightweight rifles, which is why a rifle weight of nine pounds was chosen for the recoil comparison. The numbers show that the two cartridges are very similar in recoil energy and velocity. Both cartridges/loads are slightly over the 15 ft. lb. level that an "average" hunter might consider comfortable, but not by much.
For comparison, the common .30-06/180 grain factory load generates recoil energy of about 20.3 ft. lbs. and a 12.8 fps recoil velocity in an 8 pound rifle. Compared to that, these cartridges are not so bad as long as they are fired in a rifle of substantial weight!
As this comparison has revealed, these cartridges are not far apart in most performance categories. The .257 shoots a little flatter and the .264 hits a little harder, particularly beyond 200 yards, but neither caliber has a decisive advantage in any area. They are excellent long range cartridges for harvesting CXP2 game and both will take larger game at moderate range, but there are many better choices for the latter purpose. However, for the open country mule deer hunter, the .257 Weatherby Magnum and .264 Winchester Magnum are nearly impossible to beat.
The selection of .257 Weatherby Magnum rifles and ammo is better than the selection of rifles and ammo in .264 Winchester Magnum. Perhaps more important, if you want a Weatherby rifle you will need to go with the .257 and if you want a Winchester Model 70 rifle you will be looking for a .264. That is how most hunters would probably decide the issue.
Copyright 2009, 2012 by Chuck Hawks. All rights reserved.