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.257 Weatherby Magnum


The .257 Weatherby was one of Roy Weatherby’s earliest creations and quickly became his favorite.  Introduced in 1948 the .257 is based on the .300 Holland and Holland case, shortened to 2.545" and necked down to .25 caliber. As far as Weatherby's philosophy of fast killing through high velocity went, the .257 achieved this goal in spades. This cartridge has retained a small following ever since its introduction and continues to fascinate many hunters today.


The .257 Weatherby, like all over bore cartridges, requires a minimum barrel length of 26" in order to obtain optimum performance. This cartridge was initially designed for open country work on medium game and at ordinary hunting ranges, is extremely fast killing and spectacular. Nevertheless, when loaded with soft conventional bullets, the .257 also has a well documented history of producing complete bullet failure on impact, allowing animals to escape with cruel wounds.

The key to success when using the Weatherby is matching the right bullet to the right game and conditions. As much as this cartridge has been plagued with complaints of bullet blow up, moving to the stoutest possible projectile can be just as in-effective.

For close to moderate range work, all of the recently designed core bonded bullets along with the 120 grain Partition work exceptionally well on medium game. As ranges increase beyond 150 yards, the Weatherby is able to utilize most conventional bullet designs while out at 300 yards and beyond, conventional designs show superior performance to the core bonded bullets.

The .257 Weatherby is certainly not overpowered and has relatively mild recoil for a magnum cartridge. The Weatherby is best utilized on light to mid weight game weighing bet 20kg (44lb) and 150kg (330lb) as Roy Weatherby intended. 180kg (400lb) is a safe upper limit. This cartridge is of course adequate for Elk sized game (albeit less spectacular than on lighter animals) weighing around 320kg (700lb) providing suitable bullets are chosen. 

What must be understood is that as game weights increase, so too does bullet energy absorption. While this is a good thing, a point is reached where the weight and density of the animal simply overcomes much of the energy of the projectile. In other words, a point is reached where wounding becomes somewhat narrow, especially in proportion to the size of the animal hunted. Put yet another way, wider heavier bullets driven at high velocity do more damage on large animals than small, high velocity bullets. It certainly isn’t rocket science, just the basic laws of physics.

Using 100 grain bullets, the .257 delivers high shock and broad wounding on medium game weighing up to 80kg (180lb) out to ranges of 375 yards and in some cases, further. With 120 grain bullets, the .257 is able to keep above 2600fps for high shock and broad wounding on larger animals of up to 180kg (400lb) out to 300 yards, very much on par with the 7mm Remington Magnum. At 450 and 400 yards respectively, wound channel diameters decrease resulting in slower kills. At these very long ranges, shot placement and accurate wind estimation become very important.

Factory Ammunition

Weatherby currently list five loadings for the .257 featuring Hornady, Nosler and Barnes projectiles. The light 87grain Hornady SP at 3825fps is intended strictly for varmints while the 100 grain Interlock at 3602fps and 117 grain RNSP Interlock at 3305 are both intended for use on lighter medium game.  Generally speaking, the Hornady offerings are somewhat too soft for the .257 Weatherby and prone to suffer bullet blow up at close ranges but not in a spectacular killing fashion.

Weatherby’s Nosler loadings feature the 110 grain Accubond at 3460fps, the 115 grain Ballistic Tip at 3400fps and the 120 grain Partition at 3305fps. All three are loads are very useful, the BT is dynamite on lighter game weighing less than 60kg (130lb) out to moderate ranges. The Accubond is an excellent all rounder for all medium game up to 180kg out to and beyond 350 yards while the Partition is absolutely brilliant at longer ranges, regardless of its lead tip and flat base which seem antiquated in comparison to the newer Accubond.

The stoutest .257 load is the 100 grain Barnes TSX at 3570fps. This is a good muzzle velocity for the Barnes because at lower impact velocities of 3100fps and below, this projectile tends to be slow killer. The TSX is best reserved for larger deer species and especially Boar, all of which offer a great deal of resistance to the TSX.

Hand Loading

Brass for the .257 is available throughout the U.S, Australia and New Zealand. Along with this, brass can also be formed from 7mm Remington Magnum cases. Like other Weatherby cartridges, the .257 has a very long freebore (bullet jump) which is important for eliminating pressure spikes which can occur within high charges of powder if the primer flame does not obtain an even burn.
For best accuracy, reloaders should seek to maintain optimum bullet to bore concentricity, best achieved by neck sizing rather than full length sizing.

Suitable powders for the .257 are those in the 4831 bracket along with slower powders, especially H1000. As factory ammunition is loaded to full pressures, these figures represent safe maximum working velocities including 3600fps with 100 grain bullets, 3400fps with 110 to 115 grain bullets and 3300fps using 120 grain bullets. Those who wish to avoid excessive barrel and throat wear will find best barrel life is achieved by developing loads utilizing 120 grain bullets and H1000 powder.
While it would be simple enough to suggest that this cartridge “should” only be loaded with premium bullets for best results, the .257 is not quite so limited. The stout yet explosive 100 grain Sierra GameKing has to be tried by anyone wanting a load for game weighing less than 60kg (130lb). This projectile is at its most dramatic between impact velocities of 3500fps and 3200fps or ranges between 25 and 150 yards in the Weatherby.

Slightly stouter but more suitable for game weighing right around 60kg (130lb) are the 100 grain Sierra Pro-Hunter, the Speer Hotcor and best of all, the 100 grain Nosler Partition. In some cases, the Pro-Hunter and Hotcor will not exit stout animals or those just above the suggested weight. Internal wounding is, as can be expected, dramatic.

For game weighing up to 90kg (200lb), the 100 grain Scirocco is lethal performer out to all practical ranges. Both the Nosler 110 grain Accubond and Hornady InterBond are excellent performers on game weighing up to 150kg (330lb) and adequate for game weighing up to 180kg (400lb). None of these core bonded projectiles will reach vitals of medium game with tail on shots at close to moderate (woods) ranges, but do anchor game immediately due to mass trauma.

The .257 is the ideal vessel for driving the 115 grain Ballistic Tip and 117 grain SST out to longer ranges with devastating results. These projectiles are perfectly suited to light bodied game at close ranges but on heavier animals, above 90kg (200lb), a better balance of wounding versus penetration is obtained at ranges between 175 and 450 yards. The same can be said for the 120 grain Speer Hotcor and 117 grain Sierra Pro-Hunter. For better all round performance without range limitations, the 120 Nosler Partition cannot be beaten. 

Lastly, Barnes make both 100 and 115 grain TSX projectiles. As has been reiterated throughout the course of the .257 caliber texts, these projectiles are somewhat limited in performance. That said, there are times when the TSX proves vastly superior to its competition. No other .257 projectile is as reliable or effective on large boar or other densely built game.

Closing Comments

The .257 Weatherby is quite unique. It is immensely powerful when used as intended, for light to mid weight game. Unlike other .257”, this cartridge is able to make use of a large target area out to considerable ranges. On heavy game the size of Elk, the .257 is adequate but not as ideal as a heavier cartridge. Regardless, this is a light recoiling, genuinely enjoyable cartridge to shoot.  Weatherby still offer this chambering in a variety of rifles and the cartridge covers the needs of most hunters.
Suggested loads: .257 Weatherby Barrel length: 26”
No ID   Sectional Density Ballistic Coefficient Observed  MV Fps ME
1 FL WBY 100gr TSX .216 .420 3570 2830
2 FL WBY 110gr Accubond .238 .418 3460 2924
3 FL WBY 115gr Bal Tip .249 .453 3400 2951
4 FL WBY 120gr Partition .260 .391 3305 2910
5 HL 100gr Sierra GameKing .216 .355 3600 2877
6 HL 100gr Pro-Hunter/ Hotcor .216 .330 3600 2877
7 HL 100gr Partition .216 .377 3600 2877
8 HL 100gr Scirocco .216 .429 3600 2877
9 HL 117gr Hornady SST .253 .390 3350 2915
Suggested sight settings and bullet paths           
1 Yards 100 200 340 385 425 450 475 500
  Bt. path +3 +4.3 0 -3 -6.8 -9.5 -12.5 -15.8
2 Yards 100 175 326 368 400 425 450 475
  Bt. path +3 +4.2 0 -3 -5.8 -8.4 11.4 -14.6
3 Yards 100 175 322 365 400 425 450 475
  Bt. path +3 +4.2 0 -3 -6.2 -8.8 11.8 15.1
4 Yards 100 175 304 345 400 425 450 475
  Bt. path +3 +4 0 -3 -8.5 -11.5 -18.9 -23.2
5 Yards 100 200 335 380 425 450 475 500
  Bt. path +3 +4.3 0 -3 -7.6 -10.5 -13.8 -17.5
6 Yards 100 175 307 359 400 425 450 475
  Bt. path +2.6 +3.5 0 -3.5 -7.3 -10.1 -13.2 -16.8
7 Yards 100 200 338 382 425 450 475 500
  Bt. path +3 +4.3 0 -3 -7.2 -9.9 -13.1 16.6
8 Yards 100 200 345 390 425 450 475 500
  Bt. path +3 +4.4 0 -3 -6.2 8.8 11.7 14.9
9 Yards 100 175 308 350 400 450 475 500
  Bt. path +3 +4 0 -3 -7.9 14.2 18 22.1
No At yards 10mphXwind Velocity Ft-lb’s
1 400 9.4 2669 1582
2 400 9.8 2576 1621
3 400 9.2 2589 1712
4 350 8.4 2501 1666
5 400 11.3 2530 1421
6 300 6.6 2731 1656
7 400 10.5 2601 1502
8 400 9 2717 1631
9 400 7.9 2431 1535
Note: Use factory load trajectories to plot hand loads using duplicate bullets. 110 grain Accubond trajectory can be used for 110 grain Hornady InterBond. All loads should be carefully matched to game and environmental conditions. Load No.6 shows example of optional sighting method.
 257 weatherby final.jpg

  Imperial Metric 
A .534 13.56
B .514 13.06
C R .151  
D .496 12.60
E .288 7.32
F 2.014 51.18
G .328 8.33
H 2.549 64.7
Max Case 2.549 64.7
Trim length 2.539 64.4

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