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The Ultimate Reloading Manual
Wolfe Publishing Group
  • alliant reloading data
  • reloading brass
  • shotshell reloading
The Ultimate Reloading Manual
load development

Updated 257 Weatherby Magnum Big-Game Loads

Author: Patrick Meitin
Date: Jun 18 2024

Bullets used to work up big-game hunting loads for the 257 Weatherby Magnum included,
from left to right: Cutting Edge Bullets 90-grain Copper Raptor, Badlands Precision 95-grain Bulldozer-2,
Hammer Bullets 95-grain HHT, McGuire Ballistics 95-grain Copper Rose, Barnes 100-grain TSX,
Nosler 100-grain Expansion Tip, Hornady 110-grain ELD-X and Nosler 115-grain Ballistic Tip Hunting.

My close friend, Kelsey Denton, owns not only a beautiful piece of property in South Park, Colorado, but he has a Weatherby Mark V Accumark chambered in 257 Weatherby Magnum that he uses while hunting that property’s abundant Rocky Mountain elk. There was a time when the 257 Weatherby Magnum would have been considered a shoo-in for such duties, as it was in fact, considered perfectly adequate for taking Cape buffalo by an enthusiastic cadre of American hunters who believed speed was the solution to all things related to big-game terminal ballistics. Today, we seem to have become increasingly cautious in our cartridge choices, believing nothing less than a 300 Winchester Magnum is required to down American elk, as one contemporary outdoor writer of some note frequently suggests that a 375 H&H Magnum is suitable for elk.

The 257 Weatherby Magnum was one of Roy Weatherby’s
earliest creations with the concept in the late 1940s,
but it still stands as one of the flattest-shooting
big-game cartridges around.

I grew up successfully tagging bull elk with my trusty 243 Winchester (handloaded with Nosler’s Partition) and later a 25-06 Remington, so I never really bought into the entire magnum program. During 23 years of guiding paying elk hunters in New Mexico’s renowned Gila region, I generally had more confidence in the sport toting a love-worn 270 Winchester or 30-06 Springfield than the dude carrying a custom magnum mountain rifle they had special ordered – specially for their long-awaited “Land of Enchantment” adventure.

So, when Kelsey asked me if I thought his 257 Weatherby Magnum was up to the task of the elk hunting he planned following his recent retirement, I did not hesitate to offer an immediate thumbs-up.

The argument for larger rifles usually hinges on limited time, the pressure of the huge investment in resources associated with a guided hunt (or the difficulty of securing a lottery tag in today’s highly-competitive market), and ultimately, the pressure to shoot when presented a less-than-ideal shot angle. I would counter by pointing out that questionable shots shouldn’t be taken regardless of the cartridge chosen and that modern controlled-expansion bullets have greatly expanded “smaller” cartridges killing capabilities. Not that there is anything small about the 257 Weatherby Magnum.

So, we set out to develop big-game loads for Kelsey’s rifle – a project that proved exceedingly frustrating. It became increasingly evident as we proceeded with testing that the Weatherby’s traditional 1:10 rifling twist was marginally compatible with many of today’s modern high-ballistic coefficient (BC), high-sectional-density bullet offerings. We discovered some good loads to be sure, but it required an excessive amount of shooting. The 257 Weatherby Magnum might serve as an example of too much of a good thing, which makes it exceptionally finicky. The 25-06 Remington, by comparison, is much better balanced and easier to wring accuracy from it in just about any rifle it is chambered in, at a sacrifice of 150 to 200 feet per second (fps) on average – compared to the Weatherby quarter bore.

During Kelsey’s last visit, I commented on the quality of his rifle case in direct relation to modern airline travel. That observation proved a portent of things to come. After all the work invested in load development and days of shooting, his cased rifle fell from a baggage cart and was run over on the tarmac, destroying that case and putting a bend in the thin barrel. Perhaps this was a blessing in disguise. The rifle was summarily dispatched to Wayne York of Oregunsmithing in Pendleton, Oregon, and fitted with a new Lilja barrel with a more contemporary 1:9 rifling twist. Wayne cleaned up and trued the action, installed the new tube and lapped the bore for half the price quoted by a noted Houston, Texas, gunsmithing firm and it was done in a quarter of the time.

This proved a sound investment. The frequent 4- to 6-inch scattergun groups produced by the original 1:10 twist barrel disappeared with the preferred bullets, with only one group breaking 3 inches and the overall average emerging as something closer to 1.45 inches. In other words, perfectly acceptable big-game accuracy all the way around (if not the varmint-shooting accuracy I normally strive for). I learned enough in that first series to understand what powders generally worked best in this cartridge. That heavily influenced powder selection, while also attempting to avoid more exotic powders and sticking to those I actually believed Kelsey could secure in these strange times of component shortages caused by continuing supply-chain issues (particularly from foreign countries) and hobby hoarding. A quick check of MidwayUSA’s website during testing revealed that most of these powders were in stock (except the Alliant and Vihtavuori products). This approach also resulted in fewer powders and more bullets included in this series.

Kelsey will be using this rifle for not only elk, but pronghorn and mule deer, as well as Texas white-tailed deer and hogs, so we were also seeking faster loads promising Weatherby’s famous laser-like trajectory. Kelsey has also bought into the environmentally-friendly aspects of monolithic copper bullets, while I view them as offering superior terminal performance when asking a “marginal” (debatable in this case) cartridge to perform out of its weight class. So, mono-copper were well represented, with a couple of modern lead-core bullets added at the heavy end.

Cutting Edge Bullets’ 90-grain Copper Raptor shot best with 66.5 grains of Winchester 760.
That group printed into .60 inch and clocked at a sizzling 3,943 fps.

We kicked things off with Cutting Edge Bullets’ 90-grain Copper Raptor, a boat-tail bullet holding an oversized polymer tip occupying a generous hollow point that results in multiple cutting edges spinning away from the main shank after a couple inches of penetration, the solid base pushing through. The Raptor includes a .360 G1 BC. This bullet was paired with Winchester 760 (same as Hodgdon 414) and H-4350, with all groups averaging 1.58 inches, and both powders producing the sub-MOA groups we ultimately sought. H-4350 started well with a .72-inch group at a respectable 3,732 fps using 64 grains of powder, groups stayed inside 2 inches while working toward the maximum load and velocity topping out at 3,818 fps. W-760 proved remarkably quick, hitting 3,977 fps with a maximum load of 67.5 grains of powder. The highlight, though, was a .60-inch group sent at 3,943 fps using 66.5 grains of powder. That kind of velocity would allow holding center vitals on even a dainty pronghorn from 100 to maybe 350 yards, while also delivering death-blow impacts.

Badlands Precision’s sleek 95-grain Bulldozer-2 produced the
best group of the entire test – .38 inch at 3,552 fps –
when seated over 72.5 grains of Alliant Reloder 25.

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