Best, Most Practical Caliber for Big Game?

First, let’s get our terminology straight. Most of us, me included, constantly mix the terms “cartridge” and “caliber.” Properly, caliber means bullet diameter. The Europeans keep it pretty simple, almost always naming a cartridge by bullet diameter in millimeters, then case length in millimeters, followed by the originator—as in 7x57mm Mauser. Americans play fast and loose with the numbers and few non-metric cartridges—.308 Win., .264 Win. Mag., .257 Roberts, .338 Lapua—accurately reflect the bullet diameters they use.

In America, the .30 caliber has long been our most popular rifle bullet diameter, at least across hunting and competitive shooting. What we call .30 caliber is a classic example of rounding of numbers. Since 1892, starting with the .30 U.S. Army (.30-40 Krag), .30 caliber refers to a bullet that is actually .308-inch in diameter. The many cartridges that use this bullet diameter may be called .30 or .300—or approximated, as in .307 Win.

In the late 1880s, when smokeless propellants became available, the world’s militaries started switching from large-caliber blackpowder cartridges to faster cartridges of lesser calibers with smaller cases. Early favorites included 6.5mm (.264 inch), 7mm (.284 inch), and 8mm (.32 caliber). In adopting the .30-40 Krag, which employed a .308-inch bullet and, using the old blackpowder convention, propellant charge of 40 grains of smokeless powder, we were behind most European powers in going smokeless.

However, the .308-inch bullet of the .30-40 Krag established what we still consider .30 caliber. This became written in stone by the .30-30 Win. in 1895 and the .30-06 (properly .30 U.S. Government, Model of 1906). The .30-06 would remain America’s military cartridge until 1957, when replaced by the 7.62x51 NATO (aka .308 Win.)

The .30-30 and .30-06 were easily America’s dominant hunting cartridges at least into the 1960s. Both remain popular, but today, between factory cartridges, single-source proprietaries and non-standard or wildcats, there must be dozens of .30 caliber cartridges. Some, like the .300 BLK, .30 Carbine, and the .30-30, are mild-mannered. Others, like the .308 Win. and .30-06, are powerful and versatile. And then there’s a whole slew of fast magnum .30s—belted, unbelted, short, fat, long, longer and huge.

While the .30’s position seems unassailable here, it is certainly not the only choice. If your hunting interests run to game larger than deer, I could make a strong argument for either the 8mm (.323 inch) or .33 (.338 inch) as the most practical and versatile bullet diameters. But I wouldn’t get wide support because, in the United States, big game and deer are almost synonymous. And, as anyone in the rifle or ammo business can attest, once you get past .30 caliber, sales drop off quickly.

Introduced in 1925, the .270 Win. quickly became, and remains, one of North America’s most popular hunting cartridges. However, its .277-inch bullet has spawned few other cartridges—the .270 WSM and recently introduced 6.8 Western being notable exceptions. As no cartridge using a .277-inch bullet has been considered a target cartridge, this caliber has lagged behind in development of match bullets and the aerodynamic low drag bullets so popular today. I am a big fan of the .270s, awesome for deer and mountain game and fully adequate for elk. But I won’t even try to argue that the .277-inch bullet is as practical or versatile as the .30.

The other reasonable possibilities for best caliber are the 6.5mm (.264 inch) and 7mm (.284 inch). Both go back to the dawn of smokeless powder, and in the 1890s both calibers were adopted by numerous militaries.

In the early 1900s the 6.5mm enjoyed some popularity in the U.S., but support dwindled. Until recently it was an article of faith that any American 6.5mm cartridge was certain to fail. Obviously, that has changed. The 6.5mm Creedmoor is the current best-seller among sporting and target cartridges. Its popularity has greatly increased 6.5mm bullet choices, and has brought along a spate of new 6.5mm cartridges: 6.5mm PRC, 6.5mm Wby. RPM, .26 Nosler, and 6.5-.300 Wby. Mag.

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The 7x57 Mauser, the original 7mm cartridge, has always had some following in the U.S. and has remained popular in Europe. However, it wasn’t until the 1960s that America really embraced the 7mm, thanks especially to one of the most popular cartridges out there: the 7mm Rem. Mag. Today, American 7mm cartridges outnumber their European brethren and, like our .30 caliber cartridges, run the gamut from mild like the 7mm-08 to medium power in the .280 Rem. and .280 Ackley to screaming fast—the Rem. Mag. along with .28 Nosler, 7mm Wby. Mag. and a couple others.

Traditionally, both 6.5mm and 7mm cartridges have been loaded with long, heavy-for-caliber bullets. Originally, these provided exceptional penetration on game. This remains true today, but with greater weight for caliber, both the 6.5mm and 7mm are ideally suited to the long, aerodynamic, high ballistic coefficient bullets demanded by the increased interest in shooting at longer ranges.

It depends on what you want to do. Both the 6.5mm and 7mm can strut their stuff with lighter bullets than is possible with the .30 caliber, which means they can get out there with less recoil. If you want to punch paper or ring steel at extreme range, a mild 6.5mm with a super-aerodynamic 140-grain bullet is pretty hard to top. You need a 200-grain .30 caliber bullet to equal the BC, and the .30 will beat you up a lot more. Similarly, an aerodynamic 7mm bullet of about 160 grains will fly as flat as any .30 caliber bullet up to 200 grains and won’t produce nearly as much recoil.

If you’re a deer hunter I don’t think it makes much difference. Mated with decent bullets, all three calibers—6.5mm, 7mm and .30—are adequate for all deer-size game, range depending on velocity and thus case dimensions. I would even argue that the all-American .30-caliber is overkill for deer-size game.

With larger game, it depends more on velocity, bullet weight, and range. All are adequate for elk and moose, but with milder 6.5mms and 7mms shots should be kept close. With the faster cartridges, and using heavier bullets, range can be extended. However, and this is important: At similar velocities, no 6.5 or 7mm can be considered the equal of a .30 caliber with bullets of 180 grains or heavier for large game.

There are cartridges in all three bullet diameters that I have no experience with, but I have rifles chambered to various 6.5mm, 7mm and .30 caliber cartridges at differing velocities. I use them all, depending on the purpose.

Like most Americans, I’m a deer hunter. I hunt deer with 6.5mms and 7mms, and last year I took my Kansas buck with a .30-30. But, at least occasionally, I also hunt game larger than deer. So, for my money, I’m convinced that the all-American .30 is still the most versatile. For sure, it offers the greatest variety of cartridges, from very mild on up to the fastest, huge-cased magnums.

It is also available in by far the greatest range of bullet weights, from 90 to 250 grains although, honestly, I’m not certain of the utility at either extreme. However, for your purposes, the .30 caliber may not be the most practical. You may be happier with a milder-kicking 6.5 or 7mm.