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THE .257 weatherby magnum: quarter-bore king: this prototype proprietary screamer still goes the distance against anything.

ROY WEATHERBY DEVELOPED THE.257 WEATHERBY MAGNUM IN 1948, and it fit the company's cartridge paradigm perfectly. It was inefficient, overbore capacity, had serious muzzle blast and caused fragile bullets to blow up on contact with game. The very low expansion ratio made it hard on barrels, and it took considerable increases in powder to get significant velocity gains. Consequently, it took a lot of heat early on from critics and sometimes still does.

All of that criticism is well placed. But let's get one thing straight right up front: None of it matters. The.257 Weatherby exists for one reason: as a long-range killing machine for antelope, deer and similar-size game. Period, Its flat trajectory and downrange potential are legendary and have been for decades.

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In 1948 Roy went on his first African safari and killed more than 50 animals, many with his new.257. Even then Roy was a big proponent of high velocity "If you can get that small caliber [bullet] to disintegrate inside the animal, it will kill anything on the face of the earth," he wrote.

Weatherby offers a good selection of rifles chambered for the.257 WM. In addition to the top-of-the-line Mark V, the firm makes several models of the popular Vanguard, including the Synthetic, the Sporter and, reintroduced for 2012, the Sporter Deluxe--our test rifle this month. Weatherby guarantees 1 1/2-inch groups at 100 yards with proper ammunition, and we found this to be true. A new Trijicon 3-9x40 AccuPoint proved to be the perfect scope for it.

Test loads were prepared primarily with RCBS dies in a Redding Ultramag press, and an L.E. Wilson Adjustable Case Gauge was used to set the sizing die to barely set the shoulder back during resizing. This allowed the sized case to headspace on the shoulder rather than on the belt. This greatly prolongs case life and retards the development of incipient case-head separation. We also used an RCBS neck sizer, which aided case life (and was a work-saver because no case lube was required for its use).

The RGBS set has a perfectly fine bullet seater, of course, but for these tests we used a Forster Ultra Micrometer-Style Bench Rest seater. This little gem has a sliding straight-line seater perched beneath a micrometer thimble that allows adjusting bullet-seating depth in.001-inch increments. The.257 WM is a recent addition to Forster's line of Bench Rest seaters, and it was a delight to use.

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Roy Weatherby believed in giving the bullet a running start, so his rifles have prodigious free-bore--sometimes as much as 3/8 inch--and our test rifle was no exception. Everyone "knows" that for top accuracy you have to seat the bullet just short of the lands. Well, Weatherby must have missed that memo, because with the right ammo, virtually all Weatherbys shoot quite nicely, thank you. Our test rifle had plenty of free-bore, so we mostly seated bullets so that their bases were about even with the base of the neck, and everything went swimmingly (see the load table for the Cartridge Overall Length data). Early.257 WMs had 1:12 twists that would not stabilize long 117-to 120-grain bullets, but .257s are now made with 1:10 twists that will handle the heaviest .25-caliber bullets available.

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The plump.257 Weatherby case is based on a shortened and blown-out.300 H&H Magnum case, but cases for reloaders and factory ammo are readily available. Trim length is 2.539 inches. All Weatherby cartridges have the unique double-radius shoulder. Rifle lore has it that this supposedly promotes a better flow of powder gases, but even Roy admitted that it was mostly for marketing.

Due to the relatively large amounts of slow-burning powders used by the cartridge, magnum primers are a good idea. My favorites are the Federal 215 (originally developed for the huge .378 Weatherby) and CCI 250, although the Winchester LRM also worked very well in our tests. The maximum pressure for the .257 WM is 53,500 CUP.

Powder selection is likewise easy. Just look for the slowest-burning ones available from the manufacturer in question and you're pretty much set. Load data is available in all of the modern-day loading manuals. Most hunting-weight bullets do well with IMR 7828, IMR 4831 or H-483L With lighter bullets, either H-4350 or IMR 4350 is just the ticket. From Alli-ant, Reloder 22 and Reloder 25 work best. Vihtavuori has several suitable numbers, including N-160, N-560 and N-165. Norma has MRP and MRP-2 (soon to be replaced by No. 217). Ramshot Magnum and AA-3100, and Magpro from Accurate round out the lineup.

Bullet selection is a lot better than it was back in the day, with several tough bonded and monolithic designs. The Nosier Partition and several others effectively eliminate previous criticisms of the.257 WM for bullet blowups. While 75-, 87- and 90-grain bullets give high velocities, the.257 WM is first and foremost a big-game cartridge, so appropriate bullet selection really begins at 100 grains and continues on up to the 110-, 115-, 117-and 120-grainers. We tested more than 40 loads, and almost all performed well within Weatherby's accuracy guarantee. The best loads (in our test rifle) are shown in the load table, but if you don't see your favorite powder or bullet listed, don't hesitate to give them a try.

While the .257 WM is not primarily a varmint load, the 90-grain Sierra HPBT over 65.3 grains of H-4350 gave a sizzling 3,511 fps and would pretty much annihilate any small critter within sight.

At least one standout hunting load was discovered with each of the heavier bullets. The 100-grain Nosier Partition over 69.5 grains of IMR 7828 turned in the smallest group average of all loads tested, at.74 inch. Not far behind was the 115-grain Ballistic Tip at.89 inch at 2,988 fps over 68 grains of RL-25. The 100-grain Barnes TS-X over 67 grains of H-4831 gave 3,225 fps. And the 100-grain Sierra GameKing, Speer Hot-Cor and Swift Scirocco II bullets did well.

The new 110-grain bonded bullets from Hornady and Nosier are a bit heavier and will hold together no matter what. Vihtavuori N-165 and IMR 7828 were the powder picks here.

It was a toss-up between the four great 120-grain bullets. The Speer Grand Slam and Nosier Partition are perennial favorites of big-game hunters, as is the bonded-core Swift A-Frame. With near-maximum charges of H-1000, RL-25 and IMR 7828, groups were only a smidgen over an inch even.

If you need a cartridge to reach out and touch big game in the next zip code, the.257 Weatherby Magnum is an authentic original that is perfect for the job.

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WARNING:

The loads shown here are safe only in the guns for which they were developed. Neither the author nor InterMedia Outdoors Inc. assumes any liability for accidents or injury resulting from the use or misuse of this data.
BULLET BULLET CASE PRIMER POWDER CHARGE MUZZLE
 WEIGHT (CR.) VELOCITY
 (CR.) (FPS)

BARNES TS-X 100 Wby. Fed-215 H-4831 67.0 3,225
BT

BARNES 115 Wby. WLRM H-4831 63.5 3,017
TS-XFB

HORNADY 110 Wby. Fed-215 VVN-165 65,0 3,042
INTERBOND

HORNADY BTSP 117 Wby. Fed-215 RL-25 67.0 2,994
IL

NOSLER 100 Wby. Fed-215 IMR-7828 69.5 3,180
PARTITION

NOSLER 110 Wby. Fed-215 IMR-7828 69.5 3,202
ACCUBOND

NOSLER 115 Wby. CCI-250 RL-25 68.0 2,988
BALLISTIC
TIP

NOSLER 120 Wby. WLRM MRP-2 72.0 3,075
PARTITION

SIERRA HPBT 90 Wby. Fed-215 H-4350 65.3 3,511

SIERRA 100 Wby. Fed-215 H-4350 61.0 3,287
GAMEKINC BT

SIERRA 117 Wby. CCI-250 H-4831 64,7 3,028
GAMEKING BT

SPEER 100 Wby. Fed-215 Magnum 72.0 3,151
HOT-COR SP

SPEER 120 Wby. WLRM H-1000 72.0 3,154
HOT-COR SP

SPEER GRAND 120 Wby. CGI-250 Re-25 67.0 2,971
SLAM

SWIFT 100 Wby. Fed-215 H-1000 76.0 3,479
SCIROCCO II

SWIFT 120 Wby. Fed-215 IMR7828 68.0 3,054
A-FRAME SP

BULLET STD. AVG. MUZZLE COL
 DEV. GROUP ENERGY (IN.)
 (IN.) (ft-lbs)

BARNES TS-X 24 1.28 2,310 3.20
BT

BARNES 17 1.21 2,325 3.20
TS-XFB

HORNADY 20 1.20 2,261 3.22
INTERBOND

HORNADY BTSP 24 1.26 2,329 3.20
IL

NOSLER 20 0.74 2,246 3.20
PARTITION

NOSLER 16 1.27 2,505 3.20
ACCUBOND

NOSLER 8 0.89 2,280 3.25
BALLISTIC
TIP

NOSLER 7 1.23 2,520 3.20
PARTITION

SIERRA HPBT 32 1.24 2,464 3.07

SIERRA 17 1.17 2,400 3.16
GAMEKINC BT

SIERRA 26 1.25 2,383 3.21
GAMEKING BT

SPEER 44 1.26 2,205 3.16
HOT-COR SP

SPEER 16 1.17 2,651 3.23
HOT-COR SP

SPEER GRAND 14 1.16 2,353 3.20
SLAM

SWIFT 29 1.30 2,688 3.25
SCIROCCO II

SWIFT 24 1.19 2,486 3.20
A-FRAME SP
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Title Annotation:G&A RELOADS
Author:Gash, Steve
Publication:Guns & Ammo
Date:Apr 19, 2012
Words:1517
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