Roy Weatherby had an unbridled affection for velocity, and starting in the mid-1940s he released a series of proprietary cartridges designed to better the performance of existing designs. Among his original designs, the .270 Weatherby Magnum would better the muzzle velocity of the .270 Winchester by 300 fps or so, and the .300 Weatherby Magnum would surpass the muzzle velocity of the .300 Holland & Holland (the only other commercial .300 Magnum until 1963) by 350 fps.
With the introduction of the .338 Winchester Magnum in 1958, America found a big-game cartridge suitable for any and all game animals, from brown bears and moose in Alaska and western Canada, to elk across a canyon in the Rockies, yet had the oomph to reach out and touch a distant mountain goat or caribou. While essentially a unique bore diameter—only the rimmed .33 Winchester used the .338-inch-diameter bullets before the .338 Winchester Magnum was released—the popularity of the belted Winchester design inspired Mr. Weatherby to give his treatment to the new bore diameter.
The .340 Weatherby Magnum first saw the light of day in 1963, and in true Weatherby fashion, it did surpass the performance of the .338 Winchester Magnum. Where the Winchester variant would drive a 250-grain bullet at a muzzle velocity of 2660 fps, the .340 Weatherby Magnum would achieve 2960 fps, albeit from a larger case. Winchester’s initial quartet of belted magnums use a case length of 2.500 inches, in order to fit in the more-affordable long-action receiver, yet Roy opted for a case measuring 2.82 inches, with an overall cartridge length of 3.600 inches, requiring a magnum receiver. The difference in case capacity is commensurate with the huge increase in velocity, and there is an equal increase in recoil. Like all of Roy Weatherby’s cartridges, it is based on the .300 H&H Magnum case, and shares the 0.532-inch case head. The .340 Weatherby Magnum had most of the body taper removed and featured the signature Weatherby double radius shoulder, resulting in a neck measuring 0.340 inches (almost exactly one-caliber), giving plenty of neck tension.
The primary source for factory loaded ammunition is from Weatherby themselves, and they have a pair of bullets in each weight, in 225 and 250 grains. For the 225-grain bullets, a spire point cup-and-core bullet, and the Barnes TTSX. This pair will generate 4,700 ft.-lbs. and 4,400 ft.-lbs. respectively, as the spire point is moving at 3066 fps and the Barnes at 2970 fps. Weatherby’s website gives trajectory data based on a 300-yard zero, with a 200-yard point of impact 4.4 inches above point of aim. Averaging the pair, this puts the bullet at 10.5 inches low at 400 yards, and 28 inches low at 500 yards. That’s a pretty flat shooting cartridge, especially considering the fact that they will still generate around 2,000 ft.-lbs. of energy at 500 yards. Nosler has loaded the 300-grain AccuBond in the .340 Weatherby, but it is not listed on their website currently.
The 250-grain choices are another cup-and-core spire point and the excellent Nosler Partition. The heavier bullets will generate 4,800 ft.-lbs. on muzzle energy (to put things into perspective, the .375 H&H with 300-grain bullets will generate 4,200 ft.-lbs. of muzzle energy), and using that same 300-yard zero, will hit 4.6 inches high at 200 yards, 11 inches low at 400 yards and 29 inches low at 500 yards. While I'm the first to admit that I’d prefer a 200-yard zero, it illustrates the potential of the cartridge, as both an up-close powerhouse and as a solid choice at longer hunting ranges. In both bullet weights, I would personally opt for the premium bullet choices, as both the Barnes TTSX and Nosler Partition will handle those closer shots where impact velocities are high, and the structural integrity of a cup-and-core bullet can be strained. Additionally, the ballistic coefficients of the TTSX and Partition are slightly higher, so should you want to take your .340 Weatherby out to longer distances, say doing a multiple species hunt in Alaska or for plains game in Africa.
Should you want to handload for the .340 Weatherby Magnum—and at the price of factory ammunition it wouldn’t be a terrible idea, even if just for practice—your choice of bullet weights will open up considerably, say from 175 grains all the way up to 300 grains. Look to the slower burning powders like IMR4350, H4831SC, Reloder 22 and 25, IMR7828 and IMR7977, and definitely spark it with large rifle magnum primer.
Is the .340 Weatherby Magnum a deer cartridge? Well, it can be, but you will be swatting flies with a sledgehammer; that said, I've taken impala, reedbuck and other deer-sized game with a .404 Jeffery, so “too dead” might not be a thing. I feel the .340 Weatherby Magnum is a wonderful choice for the heavier North American species, as well as the bigger African antelope like zebra, eland, wildebeest, and in those countries where it is legal, it would be a good choice for the big cats. All of this comes with a caveat: you need to be able to shoot the .340 accurately.
In the recoil department, the .340 Weatherby shines; it has a fast, stinging recoil, and is not for the faint of heart. If this level of recoil doesn’t affect your shooting, no worries. But if you’re the least bit recoil sensitive, you might want to look to the .338-06 A-Square or other lighter-recoiling cartridges. A quality muzzle brake might not be a terrible idea (though personally, my ears detest them anymore), and a light rifle should be avoided.
If the .338 Winchester Magnum puts an exclamation point on the end of the hunting sentence, the .340 Weatherby Magnum highlights and italicizes the paragraph. But, after all, that’s what the Weatherby cartridges were designed to do, and the .340 Weatherby does it well.
Looking for previous installments of our "Behind the Bullet" series? We've got you covered.
• .416 Ruger
• 27 Nosler
• .257 Roberts
• 7mm Weatherby Magnum
• .300 PRC
• .350 Rigby Magnum
• .450 Nitro Express
• .17 Hornet
• 7mm STW
• 6.8 Western
• .375 Ruger
• .223 Remington
• 6.5x55 Swedish
• .416 Remington Magnum
• .300 Winchester Short Magnum
• 28 Nosler
• 6.5 PRC
• .22 WMR
• .458 Winchester Magnum
• .22 Hornet
• .280 Ackley Improved
• .240 Weatherby Magnum
• .458 Lott
• .264 Winchester Magnum
• .348 Winchester
• .33 Nosler
• .260 Remington
• .30-30 Winchester
• .416 Rigby
• .358 Norma Magnum
• .22 LR
• 7mm-08 Remington
• 8mm Remington Magnum
• .338 Federal
• .224 Valkyrie
• .338-06 A-Square
• 9.3x62mm Mauser
• .257 Weatherby Magnum
• .45-70 Government
• .300 H&H Magnum
• .25-06 Remington
• .30-06 Springfield
• 6.5 Creedmoor
• .300 Remington Ultra Magnum
• 7mm Remington Magnum
• .470 Nitro Express
• .280 Remington
• .300 Winchester Magnum
• .270 Winchester
• .222 Remington
• .45 ACP
• .404 Jeffery
• .44 Remington Magnum
• .41 Remington Magnum
• .243 Winchester
• .338 Winchester Magnum
• .357 S&W Magnum
• 6.5-284 Norma
• 8x57 Mauser
• .38 Smith & Wesson Special
• 7x57mm Mauser
• 9mm Luger
• .35 Whelen
• .454 Casull
• .375 H&H Magnum
• .45 Colt
• .22-250 Remington
• 10mm Auto
• .308 Winchester
