.300 Weatherby

.300 Weatherby Magnum
300 Weatherby.jpg
.300 Weatherby cartridge
Place of originUSA
Production history
DesignerRoy Weatherby
Parent case.300 H&H Magnum
Case typeBelted, bottleneck
Bullet diameter.308 in (7.8 mm)
Neck diameter.336 in (8.5 mm)
Shoulder diameter.492 in (12.5 mm)
Base diameter.512 in (13.0 mm)
Rim diameter.531 in (13.5 mm)
Case length2.825 in (71.8 mm)
Overall length3.562 in (90.5 mm)
Rifling twist1-10
Primer typeLarge rifle magnum
Maximum pressure65,000 psi (450 MPa)
Ballistic performance
Bullet mass/type Velocity Energy
150 gr (10 g) SP 3,540 ft/s (1,080 m/s) 4,173 ft⋅lbf (5,658 J)
165 gr (11 g) SP 3,390 ft/s (1,030 m/s) 4,210 ft⋅lbf (5,710 J)
180 gr (12 g) BST 3,250 ft/s (990 m/s) 4,223 ft⋅lbf (5,726 J)
200 gr (13 g) Partition 3,060 ft/s (930 m/s) 4,158 ft⋅lbf (5,637 J)
220 gr (14 g) Rn-Ex 2,845 ft/s (867 m/s) 3,954 ft⋅lbf (5,361 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. The Weatherby was first introduced in 1944, and the .300 Winchester Magnum was introduced in 1963.[2]

In recent years, Remington, Winchester and Ruger have produced rifles in this caliber, and most major ammunition manufacturers now supply factory loads.[3]


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

When comparing the .300 RUM and the .300 Weatherby Magnum, however, there is a 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 pressures, and as a consequence, surpass the .300 Weatherby in power.

The .300 Weatherby is commonly used by big-game hunters all over the world.[4]

See also[]


  1. ^ a b .300 Weatherby Magnum page at Weatherby
  2. ^ Bullets, Speer (2009). Speer Bullets Reloading Manual #14. Speer. p. 525. ISBN 978-0-9791860-0-4.
  3. ^ Bullets, Speer (2009). Speer Bullets Reloading Manual #14. Speer. p. 540. ISBN 978-0-9791860-0-4.
  4. ^ .300 Weatherby by Chuck Hawks (subscription required)(subscription required)