Barrel Length In Rifles

Hunters like fast bullets. Speed increases kinetic energy and flattens trajectories. That means game is easier to hit and hit harder. This can be done by shooting larger quantities of powder, lighter bullets or both. But it can also be accomplished with a longer barrel. A 24-inch barrel can add 100 fps to the same bullet fired by the same cartridge in a 22-inch barrel. Maybe 200 fps better than a 20-inch barrel. So why aren’t all barrels long?

Let us count the ways. Longer barrels:

  1. Are more inconvenient. They snag overhanging limbs and rocks, are harder to get in and out of vehicles, scabbards, cases.
  2. Weigh more.
  3. Are less accurate than short barrels.

Ron Spomer

Wait a minute? Less accurate? Well, intrinsically, but not absolutely. In a given circumference, a longer barrel is less accurate than a shorter barrel because it’s more prone to flexing. Make it thicker and heavier and it becomes stiffer and less flexible. So short and fat should be more accurate than long and skinny.

Here’s how it works: When a bullet explodes down a barrel, heat, friction and pressure (as much as 65,000 pounds per square inch from some cartridges) make barrels swell, jiggle, wiggle, vibrate, and oscillate. If the muzzle is in the midst of a violent motion in any direction when the bullet departs, said bullet is thrown in that direction. If the oscillations are inconsistent shot-to-shot, accuracy suffers.

Because long, thin barrels whip and oscillate more than stiff ones, the shorter ones in a given diameter should be more accurate. Long, thin barrels also warp (expand and contract) more as they heat and cool. This is why target and varmint barrels are built thick and heavy. They are more consistently accurate this way.

But, and this is an important but, hunters don’t often shoot so many consecutive shots that their barrels heat up enough to change point of impact. The game is either dead or missed and gone. And hunting rifles don’t have to park five shots inside a half-inch to win the day. Aim center chest on a deer and if the bullet ends up 4 inches in any direction, you still hit the vitals. Thus, long barrels can be OK, but the question is, what benefits do they offer?; well, those velocity and energy gains mentioned earlier. Going from a 20-inch to a 24-inch or even 25-inch barrel in a given caliber can provide the equivalent of going to a magnum cartridge. Make your 308 Win. shoot as fast as a .30-06 or the .30-06 nearly match a 300 Win. Mag.

As a rule, which varies wildly due to the kinds of powder burnt, relative bullet weight and more — you can gain from 25 fps to 50 fps with every inch of barrel, sometimes as much as 75 fps. Is this worth it? It depends on how you tolerate carrying a long barrel. Hunters on the high plains, who could hike all day with a 10-foot pole sticking over their shoulders and never hit anything, suffer few ills from lugging 26-inch barrels. But an elk hunter in dark timber sometimes cusses a normal, 22-inch barrel. That’s why some rifles come with 18-inch barrels. And they work just fine.

I once used a 7mm-08 with 18.5-inch barrel to take a mountain goat at 350 yards and a massive caribou at 125 yards. No misses. Why? Because I memorized my trajectory tables. Once you know your bullet drops a certain distance at certain ranges, it’s easy to aim to compensate for that drop. So what if you have to aim 2 inches higher at 300 yards because of an 18-inch barrel. Two inches? On the 16-inch vitals of a big game animal’s chest, big deal.


Rifle barrels come in many
lengths. Does it make
a significant difference
in performance?

What about loss of energy, of so-called “knockdown power?” Game rarely notices it. Seriously. One hundred, even 300 fewer foot pounds of energy won’t matter as long as the bullet penetrates the vitals. And that happens with the right bullet even at ridiculously slow terminal velocities.

The conclusion? Choose barrel length based on comfort and convenience more than ballistics. Unless you’re more concerned about knowing you have maximum velocity and energy than getting your game, long barrels really don’t matter. Long or short, as long as you know and understand your trajectory, you’ll do just fine.

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Ron Spomer has been photographing and writing about the outdoors for nearly four decades. He’s written seven books, hunted on six continents and been published in more than 120 magazines. He’s currently rifles’ editor at “Sporting Classics,” Travel columnist at “Sports Afield,” Field Editor at “American Hunter” and “Guns & Ammo” — Optics Columnist at “North American Hunter,” Contributing Editor at “Successful Hunter,” Senior Writer at “Gun Hunter,” and TV host of “Winchester World of Whitetail.” He will write on Shooting Tips weekly for sportsmansguide.com. You can read his blogs and catch some of his YouTube videos at www.Ronspomeroutdoors.com.

 

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