On my first trip to New Zealand, I brought along a .338 to conduct my various slaughters, and fell into a conversation with a fellow hunter who was a fan of the .340 Weatherby, whose bore is also .338, but which is a much larger, fiercer cartridge.

“When I took my .340 to Africa,” he said, “the trackers called it ‘Boomplop,’ because they’d hear the boom of the rifle and simultaneously, the ‘plop’ of whatever it shot hitting the ground.”

That’s been my experience with the cartridge. Ross Seyfried said it most eloquently: “If it can’t be done with a .340, it probably can’t be done with a rifle.”

I got involved with the cartridge in 1971 because I wanted something of .338 caliber, and no one made a southpaw .338 Winchester, but Weatherby made the .340 left-handed, and I bought two, a plain one and a fancy one. I shot an elk and a mule deer with the plain one in 1972, and both animals went down in their tracks, which is pretty much the way things have gone ever since with that cartridge, right up through an Alaska moose in 2006.

The cartridge was introduced in 1962, and like the other long Weatherbys, is based on the .375 H&H case, necked down, given a Venturi shoulder, and de-tapered. It holds gobs and gobs of powder, and with a 24-inch barrel produces 200 fps to 250 fps more than the .338. Weatherby has always used a 26-inch barrel for this round, and I have always rushed to the gunsmith to have 2 inches lopped off, but it will give you even more velocity. A twenty-two inch barrel, which does very well for the .338, is mere foolishness with the .340.
The .340 occupies several niches: One is as a delivery system of Major Wallop at long range. You can crank a 210-grain bullet (much better than the 200) up to nearly 3,000 fps in a 24-inch barrel and it will pound the daylights out of whatever you want to pound way, way out there. Another niche is inside of 300 yards, as a general overwhelmer of whatever poops, where it’s at its best with 250-grain bullets, which I was able to get moving at 2,850 fps.

If you’re interested in really big game, the slug of choice is the 275-grain Swift A-Frame, which is what I used to maul my moose. It’s the equivalent of a .375 H&H, maybe a bit better, because the bullets are so long. I was getting 2,600 fps and change, and I would not hesitate to use the round on a Cape buffalo were it legal, which it ain’t in most places.

The price for all this is recoil, which is quite grim. In a 10-pound rifle, the 250-grain bullets will give you around 34 foot-pounds of kick, which is right up in .375 H&H territory. If you get a .340, you want it to be about 10 pounds with scope, not less, and make sure that scope is a long way from your eye. Either that, use or a muzzle brake. (I would prefer the recoil.) The muzzle blast is also very impressive.

This is a specialist’s cartridge. For the majority of shooters the plain old .338 is much easier to handle and will result in fewer trips to the orthopedist. But if you can stand up to it, the .340 is truly Boomplop.