.308 in 20" , 24" and 26" barrel lenght, what you will get and what you will lost?

[ShootAndHunt]

Just keep wondering the barrel length thing. Many articles said that in the .30-06 or bigger caliber you'd better go for 24" inch barrel. But how about the .308 Win? What is the difference from a 20" , 24", or 26" barrel, especially all bull barrels?

a 20" might be more handy, but how much does it sacriface the range, killing power and accuracy, say, at less than 600 yds range and often between 100 and 400 yds?

a 26" might be better in accuracy, but how better? (in contrary I heard that sometimes shorter barrels might have some advantage in accuracy since they are stiffer), but it might be only suitable for bench and target, isn't it just cumbersome to carry such a rifle when hunting?

a 24" sound like a good balance? But the questions what is the obvious advantage of it when compared to a 20" bull barrel?

Prefer to go shorter, but is 20" good enough for my use?

 

[Dave R]

FWIW, the Speer #13 reloading manual says that their 22" barrel test rifle recorded velocities equal to, or slightly GREATER than, their 24" pressure barrel. So a barrel longer than 22" on a .308 may not get you any more velocity, unless handload a slower powder or something.

My .308 has a 22" barrel and I have never longed for more. But weight is an issue for me.

I do believe some "sniper rifles" in .308 have longer barrels--24" or 26". Must be some reason for that. I just don't know what it is.

 

[Jim K]

There is no hard and fast rule because of differences in barrels, powder, bullet, etc. But a good rule of thumb is 50-75 feet per second gain or loss per inch of barrel in those barrel lengths.

So a 20" will give you about 200+ fps less than a 24" barrel. But the shorter barrel is a lot handier. But the shorter barrel will also give more noise and muzzle blast. It really all boils down to what YOU like.

Jim

 

[hksw]

FWIW, the Speer #13 reloading manual says that their 22" barrel test rifle recorded velocities equal to, or slightly GREATER than, their 24" pressure barrel.

So these values were obtained from two different (typesof) barrels and not the same barrel at different lengths?

 

[Art Eatman]

hksw, probably two different rifles. A guy goes out and test some loads one day; it might be days later and a different guy testing other loads.

Used to be, factory data was developed with 26" barrels. Then came all the various bullet makers and powder manufacturers, all publishing data. Multitudes of different brands of rifles, and quite a variance in what length of barrel some tester used.

So, there's a very generalized rule of thumb that's reasonably approximate, but not exact. That is, cartridges of the '06 sort (including the .25-06, the .270 and maybe the .300 H&H); will lose about 75 ft/sec/inch from your reference barrel. In the .308 size, figure roughly 40 or 50 ft/sec/inch. For the larger Maggies, 80 to 100 ft/sec/inch.

Again, this is not any exact thing. About all you can do is figure you'll gain or lose *roughly* that amount if you're longer or shorter than the datum barrel used in some velocity chart.

FWIW,

Art

 

[ShootAndHunt]

Hmm, I knew that the bullet velocity might lose about 50 fps per inch of the barrel. But how about the accuracy, kill power differences at up to 600 yds, and most often 100 to 400 yds? Are they quite different or just barely noticeable in the above condition?

 

[Art Eatman]

The operating theory is that a shorter barrel is stiffer, and therefore is a bit more accurate. Barrel weight is probably more important, though.

Generally, animal-hunting means shots inside 300 yards, in the interest of precise shot placement, adequate penetration and a clean kill. "Clean kill" is of no interest if you're talking about military-type needs on people. Anyhow, for typical cartridges in most hunting situations, there ain't a nickel's worth of difference from 100 to 200 ft/sec less than "max".

There are specialized differences, of course. "Bean Field" rifles are set up to get the maximum performance, since the hunter knows in advance that his shots will be longer than are common.

Another factor that most don't seem to think about is whether or not the distance to the target is accurately known. ALL cartridges' bullets start dropping off at a serious amount, after 300 yards. If you're zeroed at 200, most rifles' drop is about 6" at 300, and around 18" to 24" at 400. It's even worse on out there. Not all that many people can really tell the difference between 200 and 300 yards, much less know that it's "365 yards to that deer".

Another rule of thumb (How many hands does that boy have, anyway? ) is that one should limit shots to a distance at which the remaining energy is around 1,000 ft-lbs. I guess that's a sort of combination of expansion and penetration in the attempt to define "effectiveness". Much below that, and the odds for a clean kill are greatly lessened.

$0.02 and FWIW and all that...

Art

 

[Al Thompson]

Virtually no difference. Accuracy has very little to do with the length of the barrel unless your using iron sights. There is some data that short barrels shoot better due to stiffnesss, but it's very dependant (IMHO) on the quality of the barrel, not just the shortness.

 

[Dave R]

So these values were obtained from two different (typesof) barrels and not the same barrel at different lengths?

Correct. If I understand the process correctly, a pressure barrel is a specific beast with a transducer or a copper crusher in it to obtain pressure measurements. May not even be attached to a rifle, AFIK.

Point is, Speer found it interesting enough that they had HIGHER velocities in a 22" barrel than in a 24" barrel (in some loads) that they noted it in their book in a sidebar.

I suppose that some of the faster-burning powders may be burned out in 22", and the additional 2" of length just adds additional drag? At any rate, a longer barrel may not necessarily get you more velocity, depending on the load. Slower powders would probably benefit from the longer barrel more than faster powders.