The .340 Weatherby Magnum
By Chuck Hawks
The .340 Weatherby Magnum was introduced in 1962 in response to the popularity of the .338 Winchester Magnum. It is based on the .300 Weatherby case necked up to accept .338" bullets. Unlike the Winchester cartridge, the .340 requires an long magnum action. Although it has never challenged the .338 Win. Mag. in popularity, the .340 has developed a sterling reputation for use on large animals at long range and it is probably the best as well as the most popular of the full length .338 Magnums.
A-Square, Federal, and Weatherby offer factory loads for the .340. The Weatherby factory loads offer the greatest variety of bullet types and weights. Their 200 grain bullets (there are two offered) have a MV of 3,221 fps and a ME of 4,607 ft. lbs. The 210 grain Nosler partition bullet has a MV of 3,211 fps and a ME of 4,807 ft. lbs. The 225 grain Pointed Expanding bullet has a MV of 3,066 fps and a ME of 4,696 ft. lbs. The 225 grain Barnes X-Bullet has a MV of 3,001 fps and a ME of 4,499 ft. lbs. The 250 grain Pointed Expanding bullet has a MV of 2,963 fps and a ME of 4,873 ft. lbs. Last but certainly not least, the 250 grain Nosler Partition bullet has a MV of 2,941 fps and a ME of 4,801 ft. lbs. This might be the best "all-around" load for the .340.
Since the .340 is clearly designed for big animals at long range, and since there is little to choose in trajectory between the various bullet weights and loads, the trajectory of the factory load with the 250 grain Nosler Partition bullet can be taken as representative. If a scoped Mark V rifle is zeroed at 300 yards, this bullet will hit +3.9" at 100 yards, +4.6" at 200 yards, 0 at 300 yards, and -10.6" at 400 yards. This makes the .340 about a 385 yard elk rifle.
Because Weatherby factory ammunition is loaded to maximum pressure, reloaders will have difficulty duplicating the published Weatherby ballistics. For example, the fifth edition of the Nosler Reloading Guide shows muzzle velocities with 250 grain bullets and 82.0 grains of IMR 7828 powder of 2648 fps. 86.0 grains of IMR 7828 drove the 250 grain Nosler bullets at a MV of 2818 fps. These loads used Weatherby brass and Federal 215 primers, and were tested in a 26" barrel.
The .340 is chambered in the Weatherby Mark V bolt action rifle, which has a 26" barrel and weighs 8.5 pounds without sights. A scope and mount will add about another pound. This extra weight makes the .340 Wby. more pleasant to shoot than the new .338 Rem. Ultra Mag in the lighter Remington Model 700 rifle. A 250 grain bullet at a MV of about 2900 fps will generate about 37.8 ft. lbs. of recoil energy in a .340 Mag. Weatherby Mark V rifle. With the right bullet, such a load will take all of the world's game animals.
Copyright 2001, 2012 by Chuck Hawks. All rights reserved.