Barrel length and accuracy


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ndh87
March 4, 2009, 11:48 AM
Im Looking at getting a .308 bolt action and was wondering, How much of a difference in accuracy would there be between a 20 and 26 inch barrel?

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gvnwst
March 4, 2009, 11:52 AM
It depends. Short barrels can be just as accurate as a long barrel, but also give less velocity, so at longer ranges, the bullet will have more drop and windage. So, it would be a harder to hit the target.

What range are you planning to shoot at?

rangerruck
March 4, 2009, 11:57 AM
agree with gvn; generally shorter bls are stiffer, and have less of a whip effect.
However, you are losing a lot of speed between those two measurements, at least 200 fps , I would guess. but if firing out to say, 600 m, then a 20 incher will be fine.

NELSONs02
March 4, 2009, 12:01 PM
There wont be any difference in accuracy but one type of ammo/load might work well in one and not the other..... My 16" dpms .308 will shoot under an inch and so will my 24" weatherby.

SlamFire1
March 4, 2009, 03:18 PM
At high power matches, or long range matches, there are always guys wagging around rifles with "bloop" tubes on them. The tube fits on the end of the barrel and with a front sight attached, gives additional sight radius.

Because that additional sight radius means nothing to the shifting winds, and the basic inconvenience of not tripping over a seven foot long rifle (or so!), bloop tubes are the last domain of the righteous believer.

One of the shortest sight radius packages around is the AR15. Virtually a snubbie in the rifle world. Yet in match configuration it is the most accurate service rifle in the world.

Still, with a real short sight radius, you have to concentrate on a perfect sight picture each and every shot. It it ainít perfect when you break that trigger, that bullet is going strange places.

On a scoped rifle, barrel length is virtually ill relevant to accuracy. In theory shorter tubes are stiffer, assuming same barrel weight. In practice, human errors are the greatest source of errors. In equipment terms, I believe the 90-95% percent contributors to accuracy are good barrels, good bullets, and good bedding.

Zak Smith
March 4, 2009, 03:20 PM
Barrel quality and that the chamber was cut straight and concentric to the bore is more important than barrel length for accuracy. It totally eclipses any "whip" effect.

USSR
March 4, 2009, 03:48 PM
How much of a difference in accuracy would there be between a 20 and 26 inch barrel?

Accuracy is not a direct function of barrel length.

Don

LTR shooter
March 4, 2009, 03:57 PM
How much of a difference in accuracy would there be between a 20 and 26 inch barrel?

My 20" 700 LTR in .223 has turned out to be my most accurate rifle - outshooting all the 26" tactical/varmint guns I've owned. Well , I do have one 26" VLS that has not been fired yet:D

If you like the idea of a 20" .308 I say go for it.

Kurt_D
March 4, 2009, 04:31 PM
Everyone's pretty much hit the nail on the head. Unless you're planning on pushing out there to 800+ yards you probably won't see a huge difference. If you are then the 26" barrel will be able to keep a 175gr SMK supersonic and that will help accuracy.

d2wing
March 4, 2009, 09:15 PM
There are so many factors in accuracy it's hard to say if recoil changing position of the barrel offsets the increased velocity of the particular rifle and load. Bullet velocity and rifle weight make more difference I would think within
a couple inches of optimal barrel length. I dunno but I've had good luck with shorter barrels on some guns.

Art Eatman
March 4, 2009, 09:28 PM
A somewhat long but interesting article on the subject:

http://www.angelfire.com/ma3/max357/houston.html

45crittergitter
March 7, 2009, 10:38 PM
All other things being equal, a shorter barrel of the same profile will be more accurate than a longer one, although not necessarily with the same load(s).

41magsnub
March 7, 2009, 10:39 PM
That depends.. is the barrel long enough to just poke your target? :)

MachIVshooter
March 8, 2009, 07:29 AM
It's been pretty much covered above, so all I can really do is summarize.

All else being equal, the shorter tube will be more rigid, thus produce better accuracy.

Optimal barrel length, however, is dependent on cartridge and intended use. Remember, the faster the bullet, the less time there is for environment to act on it. As well, when bullets transition from supersonic to subsonic, there is a dramatic disruption in the airflow around that bullet, which has a negative effect on accuracy. This is why you see the latest purpose-built sniper cartridges using very low drag bullets fired at very high velocities. The 408 Chey-tac, while less powerful than the .50 BMG at the muzzle, has tremendous velocity combined with a very high B.C. bullet, which translates to better accuracy and more energy at extreme range.

Of course, there is the practicality end of it. You could build a .300 mag with a 3" profile barrel measuring 40 inches in length, and you'd have both the barrel rigidity and the increased velocity. You'd also have a 60 pound rifle.

JDGray
March 8, 2009, 10:52 AM
My 20" Savage 10FP is very accurate, but the 20" barrel looks a little funny:D

Caliper_RWVA
March 8, 2009, 11:03 AM
More reading material: http://www.tacticaloperations.com/SWATbarrel/

Personally, I like the looks of a longer barrel (always glance at those old flintlocks at gun shows) but you only need enough barrel to burn all the powder and get maximum muzzle velocity. If you are shooting fireballs, you probably have too short a barrel. If you are going for maximum accuracy, I'd assume you would have a scope anyways so the shorter sight radius of a shorter barrel is not part of the picture anymore.

Art Eatman
March 8, 2009, 02:44 PM
There's "adequate accuracy", which for me has generally been sub-MOA and preferably around 1/2 MOA. My 26" '06 was sub-MOA and a tad better for the first three shots. Same for my 19" .243 and for other rifles in the 22" length.

Then there are the efforts commented upon in the Houston Warehouse article, with many tests showing that 21.75 inches was the best of all barrel lengths.

"One test is worth a thousand expert opinions." They did bunches of tests.

woof
March 8, 2009, 03:20 PM
I've heard that muzzle velocity drops as barrel length decreases AND that the rate of decline is faster with smaller bullets. I don't know if that's true but I heard it on THR so it must be :). In other words, if you went from a 22 to 18 inch barrel in a .308 you would lose less proportionally that if you went 22 to 18 with a .243. I'd like something with a short barrel in an under .30 cal, but keep thinking the performance price will be higher.

MachIVshooter
March 8, 2009, 03:33 PM
In other words, if you went from a 22 to 18 inch barrel in a .308 you would lose less proportionally that if you went 22 to 18 with a .243. I'd like something with a short barrel in an under .30 cal, but keep thinking the performance price will be higher.

Lot's of variables there, and comparing the .308 and .243 (same case) is probably not the best example of barrel length affecting one cartridge more than another.

In general, though, the more powder you're burning, the more barrel you need. And that's why Short action rifles are most commonly found with 22" tubes, long actions with 24" and magnum with 26". Best combination for velocity and portability. If you a 26" barrel and lobbed it to 20", a cartridge like the .300 Ultra mag burning upwards of 90 grains of powder will be much more affected than a .308 that only uses ~50 grains.

But continuing with the example you laid out, velocity loss in flight is the product of ballistic coefficient, not bullet diameter. Long, slender bullets with maximized aerodynamic design retain velocity better than lightweight, stubby pills.

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