.257 Weatherby Mag

Norma-USA

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by Aaron Carter



If a well-versed hunter was asked to describe what he or she deemed to be the ideal whitetail or western big-game cartridge, assuredly “high velocity,” “flat trajectory,” and “hard hitting” would top the list. Interestingly, all of the aforementioned attributes—and then some—are found in a cartridge that turns 70 years old this year; that cartridge is the 257 Wby. Mag.

Although not the first cartridge in the once-proprietary “Weatherby Magnum” series—that distinction goes to the 270, which was introduced in 1943—the 257 Wby. Mag.’s popularity approaches that of the much-vaunted 300. Exuding Roy Weatherby’s “high-velocity” mantra, it is purported to have been his personal favorite; in fact, he used the cartridge to take game in size up Cape buffalo, though such is not recommended. Because of its impressive external and terminal ballistics, yet mild recoil, it’s among my favorite cartridges, too.

When the 257 Wby. Mag. debuted, there were relatively few true “high-performance” factory or wildcat big-game cartridges; in this realm, the 270 Win. reigned supreme, though Weatherby’s own 270 bested it by more than 250 f.p.s. In “quarter bores,” as they’re often coined, the two factory options best suited for stretching the distance at the time were the 250-3000 Savage (250 Savage) and 257 Roberts, which offered—and still do—respectable downrange performance. Both chamberings would eventually be “improved,” a process derived by P.O. Ackley that increased usable propellant space through the reduction of body taper and steepening of the shoulder angle, and resulting in a velocity increase upward of 200 f.p.s. Still, the 257 Wby. Mag. offered a marked improvement over its cohorts; in fact, depending on the projectile’s weight, the increase in velocity ranged from 300 to 600 f.p.s. Due to the Weatherby’s cavernous case (approximately 81.0 grs. of water), the largest gains were realized when long, heavyweight bullets—weighing upward of 120 grs.—were utilized.

Unlike the aforementioned factory chamberings, though, several wildcats approached, if not eclipsed, the velocities of the 257 Wby. Mag. Take the 25 Neider for example. Unveiled in 1920 by A.O. Neider, the 25 Neider—or 25-06 as it would be named upon its adoption by Remington in 1969—offered velocities within 200 f.p.s of the Weatherby round across the bullet weight spectrum. Even today, when the most technologically advanced propellants are used, the 25-06 Rem. still fails to catch up to the 257 Wby. Mag. The latter’s case—the same as used for the 270 and 7 mm Wby. Mag. cartridges, albeit necked down—offers about 22-percent more propellant capacity the 25-06 Rem., which, when combined with a high pressure ceiling, gives it an undeniable advantage with regard to external ballistics.

In his book Handbook for Shooters & Reloaders II, P.O. Ackley describesseveral .25-cal. wildcats with velocities that exceed those of the 257 Wby. Mag. The most intriguing chamberings are the 25 ICL Mag. and the 257 Baker Mag.—both of which employ a necked-down 264 Win. Mag. case to achieve 3,790 f.p.s. and 3,650 f.p.s., respectively, with a 100-gr. projectile. Based upon the propellant types (burn rates) and charges necessary to attain those elevated velocities, it’s possible that they were overpressure, not to mention considerably less efficient that the 257 Wby. Mag., which is already considered overbore. Then again, “efficiency” is not what the 257 Wby. Mag. or other high-performance cartridges are about.

As with 0.277” bullets, which are used in cartridges such as the 270 Win., 270 WSM, and 270 Wby. Mag., traditionally most .25-cal. bullets—which typically weigh between 75 and 120 grs.—have been less streamlined than those in 0.243”, 0.284”, and 0.308” diameters. As such, the less aerodynamically shaped projectiles shed velocity more quickly. This not only decreases the amount of energy delivered on-target, but also increases bullet drop and wind deflection, which are critical considerations for hunters who have the skillset to “go the distance.” Fortunately, companies such as Berger, Nosler, and Sierra have increased the number of .25-cal. hunting bullets exhibiting increased ballistic coefficients. For example, when a 115-gr. Nosler Ballistic Tip (with a .453 BC) is propelled to 3,380 f.p.s., and the rifle is zeroed at 300 yds., the bullet hits 7.90” low at 400 yds. and 21.50” at 500 yds. Talk about flat shooting!

Before selecting a projectile, one must determine whether or not the rifle that he or she is using has the appropriate rate of twist to stabilize it. If your 257 Wby. Mag. has a 1:10” twist, all .25-cal. bullets are fair game; however, if the rifle has 1:12”, such as found on some older Weatherby rifles, the heavier, streamlined projectiles will not stabilize. Weatherby’s antidote for the dilemma is its 117-gr. round-nose load, which works equally well with both twist rates. Also, if “working up” loads for a custom-chambered 257 Wby. Mag., note that it likely doesn’t have Weatherby’s lengthy freebore, so pressures can climb more quickly.

When pursuing deer-size game where long shots are probable, the best bullet options are the Norma 100-gr. spritzer; Berger 115-gr. Match Grade VLD Hunting; Nosler 110-gr. AccuBond, 115-gr. Ballistic Tip and 115-gr. Combined Technologies Ballistic Silvertip; and Sierra 100- and 117-gr. spitzer boattail GameKings. At close range, though, expect these cup-and-core bullets to expand violently, thus causing considerable damage to edible meat; as such, a controlled-expansion projectile, such as the Nosler Partition, Speer Grand Slam and Swift Scirocco II or A-Frame, would be preferable for closer shots. In lead-free bullets, Nosler has a 100-gr. E-Tip and Barnes has the 80- and 100-gr. TTSX, and 100- and 115-gr. TSXs. Due to their homogenous construction, these projectile retain most, if not all, of their pre-expansion weight; in fact, controlled-expansion lead-core bullets with heavier starting weights will oftentimes weigh less after expansion than the all-copper Barnes bullets due to material being “washed off.” Given their high weight retention, penetration is quite deep. The 115-gr. TSX, as well as the 115- and 120-gr. Nosler Partitions, are the preferred projectiles for pressing the 257 Wby. Mag. into service as an elk cartridge. With this, precision shot placement is imperative.

The bullet that I prefer “across-the-board” for big-game hunting with my 24”-barreled Weatherby Vanguard Series 2 Synthetic is the 115-gr. Partition, which is propelled to 3,240 f.p.s. using 70.5 grs. of Reloder 25 ignited by a Federal Gold Medal 215 Match (GM215M) primer, all contained with a Weatherby (Norma) case. Using this load, my best three-shot group at 100 yds. to-date measured 0.493”, and I’ve yet to have to track a single Virginia whitetail deer that I’ve used the combination on—all either dropped on the spot, or within sight. Seeing the Partition’s terminal performance, I wouldn’t hesitate to shoot an elk with the combination. For the 257 Wby. Mag. owner who wants to pursue elk, there’s no need to purchase another rifle, just match the bullet to the quarry and pick your shots carefully.

Lightweight, lightly-constructed .25-cal. bullets—with most weighing between 75 and 85 grs.—purpose-built for varmint and predator hunting are widely available, though rapid throat erosion and the cumulative effect of felt recoil preclude the 257’s use on a prairie dog town. That being said, the 257 Wby. Mag. has found favor with diehard predator hunters and ranch hands. Why? The cartridge’s high velocities—in excess of 3,800 f.p.s. with an 85-gr. Nosler Ballistic Tip—combined with heavier bullet weights result in less drop and wind deflection, making first-round, long-range hits on call-shy foxes and coyotes surprisingly easy. Depending on the individual bullet’s construction and its path, pelt damage could be considerable.

As for propellants, the 257 Wby. Mag. achieves its highest velocities with large doses of the slower-burning variants. In the Norma line, the nod goes to MRP and MRP-2, whereas other good options are IMR-7828, H-1000, Ramshot Magnum, and Alliant Reloder 22 and 25. The latter is my preferred propellant for the chambering.

Factory-loaded ammunition in 257 Wby. Mag. is less widely available than many other “mainstream” cartridges; however, its performance is worth the price. In its American PH line, NormaUSA offers a quality, yet economical, 100-gr. spitzer load. Norma also loads the projectile for Weatherby, as well as the Hornady 87- and 100-gr. Spire Points, and a 117-gr. round nose, all of which are InterLocks. Additionally, it offers Barnes’ 80-gr. TTSX and 100-gr TSX, and lastly, from Nosler, the 110-gr. AccuBond, the 115-gr. Ballistic Tip and the 120-gr. Partition loads. There are ammunition options for every species that 257 Wby. Mag. is capable of ethically taking. Norma also offers premium component brass under both the Norma and Weatherby names.

Due to its impressive external and terminal ballistics, the 257 Wby. Mag. is the quintessential “bean field” and western big-game rifle; in fact, it’s unlikely that one could find a chambering more well suited to long-range hunting. With today’s increased emphasis on, and desire to, stretch the distance, it’s interesting that this 70-year-old cartridge is optimally suited to do just that. And best of all, it does so without objectionable recoil.
 
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Once you have used a quick quarter bore you will never look at a 6mm,6.5 or 270 the same again and wonder why you haven't got one before even a 25 ought six.
Bob
 

bruce moulds

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but bob,
i had a 25/06 and went to a 270.
i can remember a time when a 25/270 ackley imp could beat the 257 wby for speed with the same length barrel.
this was because the norma made 257 brass was too soft in the web to take the pressure required to realize its potential.
you can tell this article is from a fair while ago, as the writer puts nosler partition high up the list for bigger game.
bruce.
 

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