Thursday, May 26, 2005

Are longer barrels more accurate?

By B.B. Pelletier

How long must a barrel be to be accurate?
There is no answer to that, because short barrels are JUST as accurate as long barrels. That's today's post in one sentence.

I just overheard an airgunner asking his buddy how much more accurate he thought a longer barrel would be for his AirForce Talon SS. As I listened, the two of them hypothesized about all sorts of accuracy influences that don't really matter or even exist.

Proof that a longer barrel doesn't increase accuracy
You can explore the accuracy versus barrel length controversy right here on the Pyramyd Air website. Let's start with a look at the Drulov DU-10 target pistol and the Drulov DU-10 Eagle target rifle. The rifle has a barrel twice as long as the pistol, yet there is NO discernable difference in accuracy. The rifle has a higher velocity as a result of a longer barrel, which means it can shoot farther than the pistol, but it does not group any better at 10 meters. Both are made for 10-meter target shooting and both are equally accurate.

A longer barrel guides the pellet for a longer time, so it MUST be more accurate. Right?
No! When it comes to accuracy, the length of TIME a pellet stays in the barrel is inconsequential. The belief that longer barrels are more accurate might harken back to the days of the Kentucky rifle, when barrels were very long. They got that way to more effectively burn their charge of blackpowder. A side benefit was the increase of distance between the front and rear sight. That made for more precise aiming, which in turn led to greater accuracy. But, the longer barrel, by itself, was no more or less accurate than a short barrel.

Need another example? Here it is. The barrel of a TX200 is less than 10 inches long, yet that rifle is one of the most accurate spring-piston rifles in the world. The TX is legend among field target shooters, who often choose it above every other spring gun made. Yet, it has one of the shortest barrels in the world of spring guns.

Swap barrels on your Talon SS & accuracy stays the same!
Back to where we began. The Talon SS provides the best way to prove this question because you can change barrels in a very short time. AirForce offers a 24" .22-caliber barrel for the Talon and the Talon SS (and in .177). The Talon SS comes with a 12" barrel; while the longer barrel increases velocity, the accuracy remains the same. According to AirForce, all three models group about 1" at 50 yards with any length barrel in either caliber.

A man who proved short barrels are deadly accurate!
Elmer Keith was a famous shooter who wrote a lot about long-range handgun shooting. He's famous for killing an elk at 400 yards with a handgun, a shot that proves extremely difficult for a marksman rifle shooter. During a demonstration for the U.S. Army, he once shot an entire magazine of Colt .45 Automatic from a government M1911A1 pistol through a man-sized silhouette at 200 yards. Most soldiers find it difficult to hit a man-sized target at 25 yards with the same gun! So, short barrels never bothered Keith!

By following Keith's instructions, I once shot several cylinders from a snubnosed Colt Agent .38 Special in front of witnesses through a football-sized target at 80 yards. So, there you have it. Long barrels, by themselves, are not more accurate. They may help by increasing the distance between the front and rear sights, but the sheer length of the tube has no bearing on how accurate the gun will be.

16 Comments:

At May 27, 2005 11:00 PM, Anonymous DAVE SMEDLEY said...

I THINK A SHORT BARREL ON A SPRING RIFLE MAY SHOOT MORE CONSISTENT BECAUSE THE PELLET EXITS THE MUZZLE SONER. THIS WOULD MINIMIZE
THE EFECT OF INCONSISTENT RECOIL
CAUSED BY THE SHOOTER NOT BEING ABLE TO HOLD THE GUN THE SAME WAY FOR EACH SHOT. IF THIS IS TRUE ,SHORT BARREL SPRINGERS MAY SHOOT MORE ACCURATLEY.

 
At May 28, 2005 7:27 AM, Anonymous B.B. Pelletier said...

Dave,

What you say has merit. The less influence the gun is able to exhert over the pellet, the more consistent it should be.

But consider this. In a spring gun the pellet does not begin to move until the piston has stopped. The major recoil has already begun before the pellet moves an inch down the bore.

That said, I feel sure the gun continues to move a lot after the pellet exits the muzzle, so you may be right about the shorter barrel having the greater accuracy potential.

I guess there are many factors to consider, where accuracy is concerned. Thanks for taking the time to write.

B.B.

 
At June 05, 2005 5:43 PM, Anonymous Anonymous said...

Does all this mean that the bull-pup configurations that you tend to see on things like the F2000 modular assualt rifle serve no purpose but to increase velocity due to extensive gas expansion? and if this is the case, then why do things like .50 caliber sniper rifles have such long barrels but would have slightly less power but the same accuracy regardless of length. And is the Walther NightHawk just as accurate at 10 yards as the shorter cp sport?

 
At June 05, 2005 6:05 PM, Blogger B.B. Pelletier said...

I don't understand your question(s)

B.B.

 
At June 05, 2005 8:26 PM, Anonymous NEKNUT said...

Under what conditions were these shots made? Having considerable time with a .45 1911A I find it diffucult to envision. Were theses shots made free hand or with a shooting rest?

 
At June 06, 2005 3:55 AM, Anonymous B.B. Pelletier said...

Keith was lying prone and holding both the front sight and a portion of the slide up in the rear sight. It took him a magazine to get on target, but once he ranged the gun, all the shots were on target.

Keith's long-range elk shot has been the subject of controversy ever since he first reported making it. You can read more about his long-range shooting and the special sights he made to do it with in his book, "Sixguns, by Kieth."

B.B.

 
At July 25, 2005 8:24 PM, Anonymous Anonymous said...

I beleive that there is an advantage to a longer barrel due to the rifling getting a better "bite" on the pellet, thus more spin and resulting stability in flight.

 
At July 26, 2005 4:25 AM, Anonymous B.B. Pelletier said...

Can you tell me more about what you mean by "bite?" I don't quite understand what you are saying.

B.B.

 
At August 02, 2005 5:44 PM, Anonymous Anonymous said...

In a longer barreled weapon, the the bullet is on the lands of the rifling for a longer period of time and makes more turns before leaving the muzzle. I don't know how theory plays into this but logic tells me that this would equate to more spin on the bullet. This would be more beneficial in long distance shooting because a bullet with less spin would start to tumble.

Regards,

Fred

 
At August 02, 2005 7:00 PM, Anonymous B.B. Pelletier said...

Fred,

The bullet spin depends on the twist rate of the rifling. A bullet will spin at the same rate (revolutions per second) from two barrels, one 20 inches and the other 5 inches, as long as the twist rate (for example, one turn in ten inches) is the same.

B.B.

 
At August 08, 2005 12:33 PM, Anonymous Anonymous said...

B.B.

You are correct regarding the turn rate, but I still believe that the barrel length figures in. An interesting test would be to fire 2 guns with the same bullets, MV, and rifling turn rate. The only difference being the barrel length. I would want to see if there was a difference in the amount of spin and range. I know where I would put my money.

Regards,

Fred

 
At January 26, 2006 3:12 AM, Anonymous Anonymous said...

If the longer barrel generated a higher velocity, then the bullet would spin faster. If the muzzle velocity was the same for any length of barrel, then all the bullets would spin at the same rate irrespective of barrel length. (This assumes all others factors remain as stated in earlier posts of course)

 
At January 27, 2006 9:31 AM, Anonymous B.B. Pelletier said...

Yor are right about higher velocity generating a faster spin.

B.B.

 
At June 07, 2006 11:52 PM, Anonymous Anonymous said...

BB,

What you said in this post is correct ONLY if the muzzle velocity is the same for both long and short barrel. Otherwise, long barrel rifles are definitely more accurate because of the centripetal inertia.

 
At February 26, 2009 3:23 AM, Anonymous Anonymous said...

BB.
How will this affect Smooth bore airguns?
I have an old underlever .22 airgun which is a smoothmore. If i reduce the length of the barrel will i still be able to take out targets at 3o yards with good accuracy?
thanks.
John - India

 
At February 26, 2009 3:56 AM, Blogger B.B. Pelletier said...

John,

The danger of cutting off the end of the barrel is removing any choke that may be there, as well as failing to crown the new muzzle correctly. But from an accuracy and velocity standpoint, cutting the barrel should make no difference.

B.B.

 

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