At what point does barrel length start to affect accuracy?


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rock jock
September 2, 2003, 03:56 PM
I have read several times that a 2" barrel is just as inherently accurate as, say, a 6" or 8" barrel (neglecting velocity loss and sight radius). Now, this does not seem intuitve to me. I would expect that the longer barrel would help to stabilize the bullet before it leaves the barrel. So, my question is, is there a minimum length below which accuracy begins to fall off significantly? Let's say you had a 1" barrel. First, for a lot of bullets, you are close to having a good portion of the bullet already occupying the first half-inch of the barrel while the round is seated in the chamber. Then once the bullet leaves the case, it encounters very little twist in the rifling (a 1:14 rifling twist would give 1/14 of 360 degrees, or 25 degrees of rotation before the muzzle). So what gives here? Expert opinions please.

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SelfProclaimedExpert
September 2, 2003, 07:37 PM
Expert opinions? Hello.

There was a test done a couple years ago in a gun rag using a 10" Blackhawk revolver and a Ranson rest. They cut and recrowned the barrel many times until it was an inch long. The groups didn't vary much.

Here's the thing: Pistol bullets, being kind of fat and slow, don't take much to stablize, compared to a long, narrow rifle bullet moving 3000 fps. Currently, the Glock 26 has one of the best accuracy reps of all the Glocks, and revolver snubbies are also known for accuracy. Short barrel can also be more rigid, helping this effect.

I think the thing to keep in mind with pistol calibers is that even a 2" barrel still produces most of the velocity of a 6". The majority of the work happens in maybe the first 1/2" of rifling. This just isn't the case with rifle rounds, which may loose significant velocity by cutting down the barrel.

Obviously, there is some lower limit, dictated by caliber, velocity, twist rate and powder. But it's too small to worry about.

CWL
September 2, 2003, 09:09 PM
Well, since barrels are nothing more than a straight tube really. All tubes should theroetically point at exactly the same spot downrange, not matter what the length shouldn't they? But this is just theoritical.

Other factors do seriously play a factor in accuracy including, distance to target, enough rifling to properly stabilize the bullet, complete powder ignition, recoil of short barrel v. long barrel, sight radius, and the human element.

Standing Wolf
September 3, 2003, 09:39 PM
I believe most of the advantage of a longer barrel is the result of a.) the longer sight radius, and b.) the improved balance of the firearm in the hand. All three of my short-barreled guns are uncannily accurate, which is to say: about as accurate as longer-barreled guns.

444
September 3, 2003, 09:43 PM
I have seen blurbs in magazine articles, including a recent edition of Handloader magazine where the author unscrewed the barrel completely off the frame and fired the rounds out of the cylinder. They were able to get decent close range groups.

10-Ring
September 3, 2003, 11:51 PM
For me the challenge is in the shorter sight radius (as Standing Wolf has mentioned). But, w/ enough practice & patience, accuracy can be maitained.

Dave R
September 4, 2003, 09:59 PM
So why doesn't someone but a good, barrel-length-independent sight on a snubby and go hunting?

A snubby with a scope or a red-dot taking a deer--that would be serious bragging rights.

But no one does it. Must be some reason...

JohnKSa
September 4, 2003, 11:18 PM
Dave R,

No one does it because you get a big velocity loss going from 6" of barrel to 2" of barrel.

Accuracy isn't the only thing you need from a gun.

Factors relating to accuracy. (Purely barrel issues--not aiming/shooter issues.)

Barrel quality of materials and manufacture. (Length is irrelevant.)
Barrel stiffness. (Somewhat length dependent--shorter is better.)
Crown quality. (Length is irrelevant.)
Bullet Stabilization. (Somewhat length dependent see below.)

Shorter barrels are stiffer and therefore tend to be MORE accurate.

At some point with a VERY short barrel, the velocity loss may be so great that you beging to have problems getting enough spin on the bullet to stabilize it. This is really pretty theoretical because you would be talking about a barrel that was VERY short or a gun that was poorly designed for the ammunition being used.

Anyway, what it comes down to is that in the practical world, a shorter barrel is usually more accurate than a longer barrel that is identical in all other ways.

Sight radius is an AIMING issue, not an accuracy issue. The longer the sight radius the more accurately you will be able to AIM, but in a machine rest, the longer sight radius won't shrink your groups.

In the practical world, shorter is also better from a shooter motion standpoint. The shorter the barrel, the less time shooter motion can act on it.

It doesn't SEEM right, but it is. Accuracy and barrel length are pretty much unrelated. And, the small amount of accuracy you could gain from changing barrel length would be gained from SHORTENING the barrel NOT lengthening it.

caz223
September 5, 2003, 06:46 AM
My first pistol was actually a revolver, a 4 5/8" blackhawk, in .41 mag with a red dot sight.
After a few years of basics, I could shoot a 6" swinger target at 100 yards offhand.
I think that with a little practice, I could do it with almost any good gun, short barreled or not, as long as it had a red dot or similar sight.
Iron sights, I'm ok out to 75 yards, but not a 6" target.
I used torso-sized swingers, and empty 30 pound cans of R-12 at 75 yards.
I don't really think that there's a point to reducing barrels to less than around 2 inches.
Any less, and the front sight would be touching the rear sight. (Slight exaggeration, but not much.)
I have a iron-sighted 686 snubby that has no problems hitting a empty 30 pound can of R-12 at 75 yards.
Can your carry gun do that?

jsalcedo
September 5, 2003, 07:26 AM
Someone want to explain the buntline? ;)

So what is to stop someone from taking a 2 inch barrel and putting a sleeve over it with a longer sight radius?

Would it save money? Would consumers go for it?

JohnKSa
September 5, 2003, 09:17 PM
Someone want to explain the buntline?
As mentioned a few times on this thread a longer barrel means a longer sight radius which means smaller aiming errors.

That doesn't mean that the longer barrel is more accurate, only that it is EASIER to be accurate with a longer barrel due to its increased sight radius.
So what is to stop someone from taking a 2 inch barrel and putting a sleeve over it with a longer sight radius?
A similar technique is used for competition rifles in disciplines that require the use of iron sights. The contraption you describe is called a bloop tube. Some of the higher end rifles have barrels that are actually counterbored from the muzzle end to keep the rifled part of the barrel relatively short while maintaining a long sight radius. However, due to the velocity loss, no one would counterbore to the point that there was only 2" of rifled barrel left. The example I'm thinking of had a 30" barrel with the last 6" counterbored leaving an effective barrel length of 24" but with a longer sight radius. In the case of rifle competition long range performance is very important, so you can't decrease the velocity too much or you can't reach out to the farthest targets. For closer range work, I've heard of 20" .22LR barrels that were counterbored to leave only 14" of rifling.
Would it save money? Would consumers go for it?
I don't think it would save an appreciable amount. Consumers most certainly would NOT go for it. As mentioned a couple of times on this thread, a shorter barrel reduces velocity. People compromise velocity for concealability--they are willing to lose the velocity which is highly desirable in return for a smaller package. Why would anyone want a LONG barreled pistol (impossible to conceal) that had the low velocity of a short barreled pistol?

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