The .257 Weatherby Magnum
By Chuck Hawks
The .257 Weatherby Magnum is based on the .270 Weatherby case necked down to accept standard .257" bullets. The 7mm Weatherby Magnum, by the way, is based on the same case necked up to accept .284" bullets. All of these are basically shortened and blown-out .300 H&H cases with Weatherby's signature double radius shoulder. The .257, .270, and 7mm Weatherby Magnums form a unique trio of ultra-long range cartridges, and all will work through any standard (.30-06) length action. The .257 throws the fastest hunting bullet and kicks the least, the 7mm throws the heaviest bullet and kicks the most, and the .270 occupies the middle position in both velocity and recoil. There is a good deal of overlap between the capabilities of the three calibers, and all are excellent long range big game cartridges.
The .257 is one of the early Weatherby calibers, designed in 1944. It is one of the most popular Weatherby calibers, second only to the .300 Mag., combining very high velocity, flat trajectory, and tolerable recoil. It is reputed to have been Roy Weatherby's favorite cartridge. He used it to shoot a great deal of game, including a Cape buffalo, while testing his theories about the killing power of high velocity bullets.
The big Weatherby belted magnum case has even greater capacity than the .25-06 Remington, and the .257 Weatherby can achieve velocities 100-200 fps higher than a .25-06 at similar pressures. Because they are loaded to very high pressure (53,500 cup) and Weatherby Mark V rifles chambered for the .257 Mag. now come with 26" barrels (and perhaps because Weatherby's ballistics are a bit on the optimistic side) Weatherby's factory loads claim about a 300 fps advantage over typical .25-06 factory loads.
I have read that the older (European made) Weatherby rifles in .257 were rifled 1 turn in 12 inches and would not stabilize 120 grain spitzer bullets. This may explain why Weatherby literature from the 1970's recommended the 100 grain bullet as the best all-around choice for the .257 Wby. Current production Mark V rifles are rifled with a 1 in 10 twist and have no problem stabilizing 120 grain spitzer bullets.
Weatherby offers several factory loads for the .257 Mag. The lightest bullet available is an 87 grain Hornady Spire Point Bullet at 3825 fps, which is the varmint and predator load for the caliber. For medium game such as deer and the smaller antelope species at long range there is a 100 grain Hornady Spire Point bullet at 3602 fps and a 115 grain Nosler Ballistic Tip bullet at 3400 fps. For woods and brush country hunters there is a 117 grain Hornady Round Nose bullet at 3402 fps. For larger or tougher game Weatherby offers a 115 grain Barnes X-Bullet spitzer at 3400 fps, and a 120 grain Nosler Partition spitzer bullet at 3305 fps.
Due to the very high impact velocities at normal ranges, a big game bullet for the big .257 Magnum should be of the controlled expansion type that will not shed its jacket on impact. The best general purpose big game loads are probably the 115 grain Barnes X-Bullet (SD .249) and the 120 grain Nosler Partition bullet (SD .260), particularly for large animals like North American caribou and elk, Scandinavian moose, and African plains game.
The 100 grain Hornady Interlock Spire Point bullet at its catalog muzzle velocity (MV) of 3602 fps has muzzle energy (ME) of 2826 ft. lbs. This is the highest velocity achieved by any Weatherby cartridge with a bullet suitable for hunting medium size big game. At 400 yards the velocity is still 2500 fps and the energy 1388 ft. lbs. The trajectory of this load looks like this (Weatherby figures): +2.4" at 100 yards, +3.1" at 200 yards, 0 at 300 yards, and -7.7" at 400 yards. Zero this load to strike 3" high at 100 yards in order to maximize the point blank range and the bullet never rises or falls more than 4.3" from the muzzle to 390 yards. This is the ultimate ultra-long range deer, antelope, sheep and goat load.
The 115 grain Barnes X-Bullet at an advertised MV of 3400 fps has ME of 2,952 ft. lbs. At 300 yards the figures are 2711 fps and 1877 ft. lbs. The trajectory of the 115 grain Barnes bullet looks like this (Weatherby figures): +2.7" at 100 yards, +3.4" at 200 yards, 0 at 300 yards, and - 8.1" at 400 yards. This is also an excellent ultra-long range load for the .257 Wby, and perhaps the best all-around load for the caliber.
The Weatherby factory load with the 120 grain Nosler Partition bullet at a claimed muzzle velocity (MV) of 3305 fps has muzzle energy (ME) of 2,910 ft. lbs. At 300 yards the figures are 2570 fps and 1760 ft. lbs. The trajectory of the 120 grain Nosler Partition bullet looks like this (Weatherby figures): +3" at 100 yards, +3.7" at 200 yards, +2.4" at 250 yards, 0 at 300 yards, -3.7" at 350 yards, and -8.9" at 400 yards. This load makes the .257 Wby. Mag. about a 350 yard deer rifle, and a potent large game rifle.
In addition to Weatherby, Federal Cartridge also loads for the .257 Magnum. Federal offers two Premium loads, both with 115 grain bullets at a MV of 3150 fps and ME of 2535 ft. lbs. One is a Nosler Partition bullet, and the other is a Trophy Bonded Bear Claw bullet. At 300 yards the velocity of the Nosler bullet is 2440 fps and the remaining energy is 1515 ft. lbs. At the same distance the Trophy Bonded bullet is traveling at 2400 fps and retains 1470 ft. lbs. of energy. The trajectory of both bullets is very similar, with the Nosler bullet shooting just slightly flatter due to its somewhat superior ballistic coefficient of .389. The trajectory of that bullet looks like this: +3" at 100 yards, +3.3" at 200 yards, +1.7" at 250 yards, -1.2" at 300 yards, -5.5" at 350 yards, and -11.5" at 400 yards. With this load the .257 Weatherby has about a 335 yard point blank range on medium size big game animals.
As usual with Weatherby Magnum cartridges, reloaders will have difficulty exceeding the velocities of Weatherby factory loaded ammunition. The Hornady Handbook, Third Edition lists a maximum load using 65.7 grains of IMR 4350 powder with their 100 grain Spire Point bullet that achieves a MV of 3600 fps. The top load listed in the fifth edition of the Noser Reloading Guide for their 115 grain bullets gives a MV of 3433 fps with 69.0 grains of IMR 7828 powder. For the 120 grain Nosler Partition bullet the top MV is 3402 fps in front of 69.0 grains of IMR 7828.
it is interesting to compare the sectional densities (SD) of some of the common small bore bullets used for long range shooting. Sectional density is a crucial factor in penetration, and if other factors are equal, bullets with similar SD will have similar penetration. The 90 grain .243" bullet (SD .218), the 100 grain .257" bullet (SD .216), and the 120 grain 7mm bullet (SD .213) are quite close. The 100 grain .243" bullet (SD .242), the 115 grain .257" bullet (SD .249), the 120 grain .264"/6.5mm bullet (SD .246), the 130 grain .277"/.270 bullet (SD .242), and the 140 grain 7mm bullet (SD .248) are all similar. Also comparable are the 120 grain .257" bullet (SD .260), the 129 grain .264"/6.5mm bullet (SD .264), and the 140 grain .277"/.270 bullet (SD .261).
The .257 Weatherby Magnum burns significantly more powder than the .25-06 Remington to achieve an increase in maximum point blank range of about 40 yards with a 120 grain bullet. It is the highest performance .25 caliber cartridge ever standardized by the SAAMI.
The price for this performance, of course, is increased recoil and muzzle blast, and possibly decreased barrel life. As with any ultra-high velocity cartridge, shoot 3-shot strings at the range and allow the barrel to cool between strings. (I allow the barrel of my .257 Weatherby to cool after every shot.) Keep the barrel clean, avoid overheating, and it will give good life.
A scoped Weatherby Deluxe .257 Magnum rifle weights about 9.5 pounds. Shooting a 120 grain bullet at 3300 fps it kicks the shooter with about 14.9 ft. lbs. of recoil energy. That is less than a .264 Win. Mag., 6.5x68S, or .270 WSM rifle with bullets of comparable sectional density and velocity, and all of these calibers deliver similar energy on target at 300 yards.
With modern controlled expansion bullets the .257 Weatherby Magnum takes its place alongside the .264 Winchester Magnum, 6.5x68S, and .270 WSM (as well as its .270 and 7mm Weatherby sister cartridges), as one of the world's premier long range big game calibers. For hunting really large big game animals the 6.5mm and .270 Magnums ultimately have the advantage due to their ability to handle heavier bullets of significantly greater sectional density. But for medium to medium-large big game (up to about 500 pounds) the .257 Weatherby Magnum may be the best long range cartridge of them all.
Copyright 2002, 2012 by Chuck Hawks. All rights reserved.