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Lindcott Armory

Rifle · SAAMI

.257 Weatherby Magnum

Also known as .257 Wby Mag

Extremely fast and flat-shooting magnum.

Caliber
0.257″ · 6.528 mm
Introduced
1944
Case
Belted
Parent
.375 H&H Magnum
Primary use
Hunting, Varmint
Status
Active

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VelocityBeing verified
EnergyBeing verified
Typical grains100 · 110 · 120 gr
Identity
Introduced
1944
Type
Rifle
Origin
United States
Inventor
Roy Weatherby
Manufacturer
Weatherby
Standard
SAAMI
Status
Active
Availability
Moderate
Build
Case capacity
82 gr H₂O
Twist (typical)
1:10
Primer
Large Rifle Magnum
Case type
Belted
Pressure & range
Max pressure
65,000 psi
Eff. range
500 yd
Max range
4500 yd
Recoil
16–22 ft·lb

Introduced by Weatherby

Ballistics

Published velocity/energy data isn't available for .257 Weatherby Magnum. Parent case: .375 H&H Magnum.

Performance

Best for Withheld until verified
Best for Withheld until verified
Dimensionscase measurements · scale drawing · size vs familiar rounds

Case dimensions — the scale drawing at the top of the page is built from these.

SAAMI · approximate
Measuremmin✓
Bullet ⌀ 6.530.257 ✓
Neck ⌀ 7.190.283 ✓
Shoulder ⌀ 12.500.492 ✓
Shoulder angle 25.5°— ~
Base ⌀ 13.010.512 ✓
Rim ⌀ 13.500.531 ✓
Belt ⌀ 13.490.531 ✓
Rim thickness 1.300.051 ✓
Neck length 8.130.320 ≈
Case length 64.642.545 ✓
Overall length 81.513.209 ✓

Size vs familiar rounds

Drawn at true 1:1 — every case is accurate relative to the others. Absolute size depends on your screen's pixel density, so measuring one against a real ruler may be off. .257 Weatherby Magnum is highlighted below.

Factory loads

Verification

Being verified

Advertised FPS, energy, and BC are withheld until loads clear verification.

Suitable powders

3 reloading powders listed for .257 Weatherby Magnum, fastest to slowest. Cross-reference in the finder →

Norma MRPN170Reloader 25
Reloading costestimate cost per round vs factory

Estimate your cost per round and how it compares to factory. Inputs are yours — nothing is stored.

Cost estimate only — not load data. Charge weight is your input; follow published manuals for safe charges.

Firearms chambered in .257 Weatherby Magnum

12 models in the database chamber .257 Weatherby Magnum. Browse all →

Weatherby Mark V Hunter .257 Wby Mag 26-inchWeatherby Vanguard Back Country .257 Wby Mag 24-inchWeatherby Mark V Backcountry .300 Win MagWeatherby Mark V TerramarkWeatherby Mark V CarbonmarkWeatherby Mark V Backcountry .257 Wby MagWeatherby Mark V Carbon .257 Wby MagWeatherby Mark V Outfitter .300 Wby MagWeatherby Mark V Carbon .300 Wby MagWeatherby Mark V Outfitter .257 Wby MagWeatherby Mark V Camilla 257 Wby MagWeatherby Mark V Accumark 6.5-300 Wby Mag

Lineage

Immediate parent
.375 H&H Magnum
Family TreeOpen .257 Weatherby Magnum in the interactive cartridge family tree

Connected reference

Loads45 factory loads for .257 Weatherby MagnumReloading3 suitable powders — cross-referenceFirearmsFirearms in .257 Weatherby Magnum

History

Developed by Roy Weatherby in 1944 as his first commercial magnum cartridge. Based on blown-out .375 H&H case necked to .257. Weatherby's personal favorite cartridge. Delivers high muzzle velocity and a flat trajectory. Popular with western hunters and long-range shooters. Heavy recoil for a .25 caliber and significant barrel wear, but dramatic performance.

FAQs

What twist rate does .257 Weatherby Magnum use?
.257 Weatherby Magnum typically uses a 1:10 twist rate.
What bullet diameter is .257 Weatherby Magnum?
.257 Weatherby Magnum uses a 0.257″ (6.528 mm) diameter bullet.
Is .257 Weatherby Magnum still in production?
.257 Weatherby Magnum is active; typical availability is moderate.
What is .257 Weatherby Magnum used for?
.257 Weatherby Magnum is primarily used for hunting, varmint.
What is .257 Weatherby Magnum based on?
.257 Weatherby Magnum is derived from the .375 H&H Magnum case.
What are the best powders for .257 Weatherby Magnum?
Reloading powders commonly listed for .257 Weatherby Magnum include Norma MRP, N170, Reloader 25.

Sources & provenance

Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 43 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →