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.300 Weatherby Magnum
.300 Weatherby cartridge
Type Rifle
Place of origin USA
Production history
Designer Roy Weatherby
Designed 1944
Manufacturer Weatherby
Produced 1944
Parent case .300 H&H Magnum
Case type Belted, bottleneck
Bullet diameter .308 in (Bad rounding hereScript error mm)
Neck diameter .336 in (Bad rounding hereScript error mm)
Shoulder diameter .492 in (Bad rounding hereScript error mm)
Base diameter .512 in (Bad rounding hereScript error mm)
Rim diameter .531 in (Bad rounding hereScript error mm)
Case length 2.825 in (Bad rounding hereScript error mm)
Overall length 3.562 in (Bad rounding hereScript error mm)
Rifling twist 1-10
Primer type Large rifle magnum
Maximum pressure 65,000 psi (Bad rounding hereScript error MPa)
Ballistic performance
Bullet weight/type Velocity Energy
150 gr (Bad rounding hereScript error g) SP3,540 ft/s (Bad rounding hereScript error m/s)4,173 ft·lbf (Bad rounding hereScript error J)
165 gr (Bad rounding hereScript error g) SP3,390 ft/s (Bad rounding hereScript error m/s)4,210 ft·lbf (Bad rounding hereScript error J)
180 gr (Bad rounding hereScript error g) BST3,250 ft/s (Bad rounding hereScript error m/s)4,223 ft·lbf (Bad rounding hereScript error J)
200 gr (Bad rounding hereScript error g) Partition3,060 ft/s (Bad rounding hereScript error m/s)4,158 ft·lbf (Bad rounding hereScript error J)
220 gr (Bad rounding hereScript error g) Rn-Ex2,845 ft/s (Bad rounding hereScript error m/s)3,954 ft·lbf (Bad rounding hereScript error J)
Test barrel length: 26
Source(s): Weatherby [1]

The .300 Weatherby Magnum is a .30 caliber rifle cartridge created by Roy Weatherby in 1944 and produced by Weatherby. It has become the most popular of all the Weatherby cartridges.[1]


Roy Weatherby already had experience with other custom cartridges such as his own .270 Weatherby Magnum when he created the .300 Weatherby. Like most of his other magnum cartridges, this is based on a blown-out .300 H&H Magnum case, using the signature Weatherby double-radius shoulder.


Historically, Weatherby claimed that this is the most powerful .30 caliber magnum rifle commercially available, but the recently introduced .300 RUM and Weatherby's own .30/378 Magnum are now more powerful. Of course there are quite a few very large .30 caliber wildcat cartridges.

One must note however when comparing the .300 RUM and the .300 Weatherby Magnum the difference in factory loadings. Performance data is often listed on the side of the ammunition box for those who wish to do an in-store comparison. On average, Weatherby factory ammo is loaded to higher chamber pressures than Remington or Winchester magnum rounds. The Remington round can be handloaded to equal or even surpass the .300 Weatherby in power.

The .300 Wby is in common use by big-game hunters all over the world.[2]

See alsoEdit



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