What twist rate does .300 Weatherby Magnum use?

.300 Weatherby Magnum typically uses a 1:10 twist rate.

What bullet diameter is .300 Weatherby Magnum?

.300 Weatherby Magnum uses a 0.308″ (7.823 mm) diameter bullet.

Is .300 Weatherby Magnum still in production?

.300 Weatherby Magnum is active; typical availability is common.

What is .300 Weatherby Magnum used for?

.300 Weatherby Magnum is primarily used for hunting, long range, big game.

What is .300 Weatherby Magnum based on?

.300 Weatherby Magnum is derived from the .300 H&H Magnum case.

What are the best powders for .300 Weatherby Magnum?

Reloading powders commonly listed for .300 Weatherby Magnum include N560, Norma MRP, Reloader 19, Vihtavuori N160, among 8 suitable options.

Lindcott Armory

Rifle · SAAMI

.300 Weatherby Magnum

Also known as .300 Wby Mag

Roy Weatherby's flagship cartridge and the one that made his name.

Caliber: 0.308″ · 7.823 mm
Introduced: 1944
Case: Belted
Parent: .300 H&H Magnum
Primary use: Hunting, Long Range, Big Game
Status: Active

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VelocityBeing verified

EnergyBeing verified

Typical grains180 · 200 · 210 gr

Identity

Introduced: 1944
Type: Rifle
Origin: United States
Inventor: Roy Weatherby
Manufacturer: Weatherby
Standard: SAAMI
Status: Active
Availability: Common

Build

Case capacity: 99 gr H₂O
Twist (typical): 1:10
Primer: Large Rifle Magnum
Case type: Belted

Pressure & range

Max pressure: 65,000 psi
Eff. range: 700 yd
Max range: 1600 yd
Recoil: 35–48 ft·lb

Introduced by Weatherby

Ballistics

Published velocity/energy data isn't available for .300 Weatherby Magnum. Parent case: .300 H&H Magnum.

Performance

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

Measure	mm	in	✓
Bullet ⌀	7.82	0.308	✓
Neck ⌀	8.56	0.337	✓
Shoulder ⌀	12.50	0.492	✓
Shoulder angle	20.6°	—	~
Base ⌀	13.00	0.512	✓
Rim ⌀	13.49	0.531	✓
Belt ⌀	13.50	0.531	✓
Rim thickness	1.27	0.050	~
Neck length	8.15	0.321	≈
Case length	71.75	2.825	✓
Overall length	90.42	3.560	✓

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. .300 Weatherby Magnum is highlighted below.

Factory loads

Verification

Being verified

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

Suitable powders

8 reloading powders listed for .300 Weatherby Magnum, fastest to slowest. Cross-reference in the finder →

Reloading costestimate cost per round vs factory

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

Powder $/lb Charge (gr) Bullet $/ea Primer $/ea Brass reuses Brass $/ea

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

Firearms chambered in .300 Weatherby Magnum

12 models in the database chamber .300 Weatherby Magnum. Browse all →

Weatherby Mark V Backcountry 2.0 .300 Wby Mag 26-inchWeatherby Mark V Backcountry Ti .300 PRCWeatherby Mark V Terramark RC 6.5-300 Wby MagWeatherby Mark V Hunter .300 Wby Mag 26-inchWeatherby Mark V CarbonWeatherby Mark V Carbonmark .300 PRC 26-inchWeatherby Mark V Backcountry Ti .300 Wby MagWeatherby Mark V Backcountry .300 Win MagWeatherby Mark V CarbonmarkWeatherby Mark V Backcountry .257 Wby MagWeatherby Mark V Terramark .300 Win Mag 24-inchWeatherby Mark V Carbon .257 Wby Mag

Lineage

Family TreeOpen .300 Weatherby Magnum in the interactive cartridge family tree

Connected reference

Loads60 factory loads for .300 Weatherby Magnum Reloading8 suitable powders — cross-reference FirearmsFirearms in .300 Weatherby Magnum

History

Roy Weatherby developed the cartridge in 1944, a year before formally founding Weatherby Inc. in 1945. The .300 Wby Mag was his calling card. Its double-radius shoulder design reduces case stretching. For decades it was the most powerful commercial .30 caliber cartridge available. Celebrities like John Wayne, Roy Rogers, and Herb Klein hunted with Weatherby rifles.

FAQs

What twist rate does .300 Weatherby Magnum use?: .300 Weatherby Magnum typically uses a 1:10 twist rate.
What bullet diameter is .300 Weatherby Magnum?: .300 Weatherby Magnum uses a 0.308″ (7.823 mm) diameter bullet.
Is .300 Weatherby Magnum still in production?: .300 Weatherby Magnum is active; typical availability is common.
What is .300 Weatherby Magnum used for?: .300 Weatherby Magnum is primarily used for hunting, long range, big game.
What is .300 Weatherby Magnum based on?: .300 Weatherby Magnum is derived from the .300 H&H Magnum case.
What are the best powders for .300 Weatherby Magnum?: Reloading powders commonly listed for .300 Weatherby Magnum include N560, Norma MRP, Reloader 19, Vihtavuori N160, among 8 suitable options.

Sources & provenance

Standard SAAMI — SAAMI cartridge & chamber drawing — .300 Weatherby Magnum
Standard SAAMI — ANSI/SAAMI Z299 — Cartridge & Chamber Drawings archived
Manufacturer Weatherby, Inc. — Weatherby Ballistics Specifications Chart (PDF) · grain_ballistics, representative_gun
Manufacturer Weatherby, Inc. — 300 Weatherby Magnum — Ammunition Store Page · grain_ballistics, representative_gun archived
Manufacturer Nosler — 300 Weatherby Mag 180gr AccuBond Trophy Grade Ammunition (item 48643) · grain_ballistics, representative_gun archived
Manufacturer Hornady Manufacturing — 300 Wby Mag 180 gr. CX Outfitter (item 822124) · grain_ballistics, representative_gun archived
Manufacturer Hornady Manufacturing — 300 Weatherby Mag 200 gr ELD-X Precision Hunter (item 82213) · grain_ballistics, representative_gun archived

Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 60 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →