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Gun Barrels: The Long & Short of It

Gun Barrels: The Long & Short of It

Do You Really need the ballistic edge that a longer barrel provides?

By Jon R. Sundra

There are times when a long barrel on a rifle can be a real plus. At other times, it can be anything from a minor inconvenience to a genuine liability. As for short barrels, they exact a toll in terms of velocity, steadiness of hold and tracking, but those attributes can mean compromising in other areas when it doesn’t make sense to do so. It all boils down to circumstance and personal preference.

Are there standards for barrel length? Yes and no. For typical production bolt-action sporters chambered in non-magnum calibers, 22-inchers are the norm. For rifles firing belted rounds and the new short magnums, it’s 24 inches. Mind you, there are many exceptions, but the typical production sporter has reflected those parameters for the last half-century.

The most notable exception I can recall occurred in the early 1960s, when Remington decided to make 20 inches the standard-caliber barrel length for its new Model 700 rifle. By 1967, however, they reverted back to 22 inches and have stuck to that ever since, so their experiment with carbine-length spouts has to be considered an aberration.

With the coming of the super magnums like Remington’s Ultra Mag family and the big .378-based Weatherbys as examples, 26 inches is the standard, as it also is for just about everybody’s heavy-barreled varmint rifle. Twenty years ago, however, most production varminters wore 24-inch snouts.

So you see, nothing’s chiseled in stone. One thing that helped standardize things a bit occurred in the late ’70s when SAAMI (Sporting Arms and Ammunition Manufacturers Institute), changed the test-barrel standard for rifle manufacturers from 26 inches to 24 inches. That made a lot of sense. After all, the typical .270 or .30-06 owner whose production rifle more than likely had a 22-inch barrel had to assume a loss of around 100 fps because of his 4 inch shorter barrel. And magnum owners, though their barrels were only 2 inches shorter than nominal, still had to figure on at least a 75 fps loss.

All calibers were affected, but the two biggest losers were the .264 Win and 7mm Rem Magnums. Consider: When the standard was changed, the nominal muzzle velocity for the .264’s 140-grain factory load went from 3,200 fps to 3,030, a loss of 170 fps. And for the Big Seven’s 150-grain load, it went from 3,260 to 3,110, a loss of 150 fps! Even the .270 Win was docked from its original 3,140 fps to its current 3,060.

Thus far, we’ve been talking standard sporter-weight production guns, but within the past decade, every major arms maker has added a carbine version of its flagship rifle. Billed as ultralights rather than carbines, these rifles are the result of two basic weight-saving measures: lighter, trimmer stocks and shorter, more slender barrels. Take your average 24-inch sporter barrel that measures around .600 to .620 inch at the muzzle, bob it to 18 or 20 inches and turn it to a more slender contour, and you’ll have saved more than a pound. You’ll also have a considerably shorter gun, which to my mind is a much more dramatic change than the reduction in weight. A rifle that measures only 38 or 40 inches overall handles so differently than a 44- or 46-incher, it’s like comparing the Chevy Suburban to a Jeep Cherokee.

Situations where the carrying and handling ease of a carbine are real assets are when hunting in close cover, from treestands, on horseback or any time a hunter needs to get in and out of vehicles frequently.

This assumes you don’t require every last fps your rifle’s capable of delivering. Take Eastern whitetail hunting, for example. Any modern cartridge from the .243 Win to the .30-06 has all the power and flatness of trajectory needed to dispatch a deer out to at least 225 yards — a distance within which probably 97 percent of all whitetails are taken. That means the velocity loss realized by a short barrel is of no consequence. Even a 100-grain bullet from a .243 Win exits a 20-inch barrel at around 2,875 fps and delivers 1,200 foot-pounds of energy at that distance, and it’s the least potent of the cartridges we’re talking about here! Typically, today’s deer hunter is armed with much more capable cartridges the likes of the .25-06, .260 Rem, .270 Win, 7mm-08, .280 Rem, .308 Win or .30-06. And we haven’t even mentioned magnums, which continue to proliferate, even among deer-only hunters.

We all know that accuracy doesn’t come into question with a short barrel, providing, of course, the gun’s wearing a scope. In fact, chances are your rifle will shoot tighter groups with a 20-inch barrel than if it were 24 or 26 inches. But that assumes barrels of equal thickness, and, typically, when barrels are furnished in 18- or 20-inch lengths, they’re also trimmed down to a thinner contour, thus negating the additional stiffness that would otherwise be realized. Bottom line: There’s no loss in accuracy with a scoped carbine.

If there are no practical disadvantages to a short barrel, why would anyone need anything longer than, say, 20 inches? Well, for one thing, need has little to do with it. Let’s face it, if we all chose a caliber based on what we needed, probably 90 percent of us could hunt a lifetime using nothing more than a .270 or a .30-06 and get by very well, thank you.

Nope, need’s got nothin’ to do with it; it’s a matter of want. Most of us want the ballistic advantage of higher velocity that a longer barrel provides. And it’s really not that much of a conscious decision on our part; most manufacturers make it for us by providing the appropriate barrel length for the cartridge in question. Want a 7mm, .300, .338 Ultra Mag or one of the big Weatherbys? Then you’re going to get a 26-inch barrel. Otherwise, the velocity loss per inch would be so great as to negate a big chunk of the performance edge you’d be getting over the 7mm Rem Mag, .300 or .338 Win Mag, respectively. Choose any of the latter “standard” magnums, and anything less than a 24-inch barrel is going to nullify half the velocity edge you’d have gotten had you chosen a .280 Rem, .30-06 or .338-06.

Gun Barrels: The Long & Short of ItBut it’s not just a velocity/energy edge you get with a longer barrel, it’s steadiness of hold and more pleasant shooting that results from the added weight and length of the rifle. That goes for field shooting from any position, using any type of rest, as well as the offhand tracking of a moving animal. Personally, the tracking aspect is not a big concern for me because the only time I’ll shoot at running game is if I think it’s wounded and might escape.

So while I’m perfectly happy with a 20-inch barrel on a whitetail rifle (anything shorter is too short for my taste), I prefer 24 inches on general-purpose guns, and that goes whether the gun’s chambered for standard calibers as well as the “old” belted and new short magnums. As for the super mags, as long as we’re talking non-dangerous game, I’ll leave those to others. Not only have I never felt the need for such grossly inefficient cartridges, but I refuse to carry a 26-inch-barreled rifle, regardless of what I’m hunting or where I’m hunting.

And where dangerous game is concerned, there’s no way I’d carry anything longer than a 22-inch barrel. I can’t imagine who makes the decisions in those gun companies that furnish 24- and even 26-inch barrels on dangerous-game rifles, but I can pretty much guarantee they’ve never hunted or helped track a wounded buffalo, elephant, lion or leopard in the  long grass of Africa, or a big bear in the alders of Alaska. I have, and I can tell you that under those circumstances, shooting is invariably offhand and at close range — real close range. You want a gun that’s responsive, one that mounts and points quickly and swings through a short arc, and to hell with the few fps and foot-pounds. You’re giving up to get it. Both are utterly inconsequential inside 50 yards, where even a .375 H&H has power to spare, to say nothing of the larger .375s, .416s and .458s. And if you have the luxury of a leisurely shot from a distance, a short-barreled DGR is neither a hindrance nor a liability.

Perhaps at this point we should get a little more specific about velocity loss as it relates to barrel length and cartridge type. A general rule of thumb tells us that the smaller the caliber, the more velocity loss per inch we can expect. That’s true, but only to a point. Cut the barrel of a .22 Hornet, for example, from 26 inches to 20 inches, and you’re not going to see a dramatic loss in velocity — maybe 10-12 fps per inch. Cut the barrel of a .220 Swift that same amount, and you’ll be looking at a loss of around 30 fps per inch.

It’s not so much a function of caliber as it is the expansion ratio of the cartridge. This is a term that expresses the ratio between the volume of the cartridge case, i.e., its displacement relative to the volume of the bore. The latter, of course, changes to some extent with the length of the barrel, while the former is a constant. In other words, a .300 Win Mag has the same displacement regardless of barrel length. The ER, however, changes with barrel length.

Subscribe Today!Cartridges with high expansion ratios lose less velocity per inch than do those of low expansion ratios, regardless of caliber. To put it another way, cartridges with high ERs are more efficient. Take the 7mm-08, for example. It’s the smallest cartridge of the current commercial 7mm lineup. To impart a muzzle velocity of 2,800 fps from a 24-inch test barrel, the 7-08 requires (based on published reloading data) a propellant charge of around 47.5 grains, give or take 2.0 grains, depending on the powder being used. Cut the barrel 4 inches, and you’ll lose about 75-80 fps, or about 20 fps per inch.

At the other end of the spectrum is Remington’s 7mm Ultra Mag with a nominal MV of 3,425 fps for that same 140-grain bullet. The closest I’ve seen to duplicating that velocity among published reloading data was Hodgdon’s; their maximum load was 107 grains of H-870 for a MV of 3,350, or 75 fps less than nominal. That’s 225 percent more powder to achieve a 16.5 percent increase in velocity. Cut that 24-inch test barrel to 20 inches, and you’re likely to see a velocity loss of 200 fps, or 50 fps per inch. With the 26-inch barrels being furnished on Remington’s Model 700s chambered for the round, however, 3,425 fps is realistic . . . if you want to carry a 46 1/2-inch rifle.

In many ways, ballistics are like optics; you get nuthin’ fer nuthin’. Want steadier holding and better tracking characteristics, more comfortable shooting, less muzzle blast and recoil, flatter trajectory and more delivered energy downrange? You can have ’em all if you’re willing to tote a longer, heavier rifle. Want easier carrying and faster handling? You can have those, too, but you’ll have to give up a lot of those “paper” advantages, many of which are more academic than real. The decision’s all yours.

Reprinted from the August 2007 issue of Buckmasters GunHunter Magazine. Subscribe today to have GunHunter delivered to your home.

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