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Optimum barrel length for 308?

DXHI

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Mar 19, 2015
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290
Got a buddy that swears 20" is all that's needed however I'm inclined to use a longer barrel for more speed. I've settled on a 1/10 twist
 
There's minimal gain with longer barrels due to the case size.

Military and police snipers have been making amazing shots for decades with a 20" barreled .308

I made a big mistake going with a 24" bull barrel on my .260 AR that uses the same case.

That extra 4" really makes it difficult to maneuver around as a carry rifle or in the truck.
 
Got a buddy that swears 20" is all that's needed however I'm inclined to use a longer barrel for more speed. I've settled on a 1/10 twist

The key to this question is intended application. The .308 can be run a myriad of different ways, for different purposes, with different results.

Like you, I prefer longer barrels. I shoot 1000 yard F-Class using 155 Sierra Palma bullets @ 2990ish from my 26" barrel, which is about as hard as I can push them. They are just starting to go transonic when they reach the 1000 yard mark. Palma shooters often use 30" barrels to allow them to push the 155's to 3000+ more easily.

For shorter ranges, out to 600 yards or so, the shorter barrels shoot accurately and the velocity loss is less important. In a hunting application, the .308 isn't going to take you much further than that, so you can get away with a shorter barrel.

Regardless of barrel length, you are on the right track with a 10 twist, which will let you take advantage of the full range of available bullets.

IMO, maximum versatility and utility in the .308 is obtained in 24" to 26" barrels. If the rifle is going to see more specialized use, longer or shorter than that may be called for.
 
The key to this question is intended application. The .308 can be run a myriad of different ways, for different purposes, with different results.

Like you, I prefer longer barrels. I shoot 1000 yard F-Class using 155 Sierra Palma bullets @ 2990ish from my 26" barrel, which is about as hard as I can push them. They are just starting to go transonic when they reach the 1000 yard mark. Palma shooters often use 30" barrels to allow them to push the 155's to 3000+ more easily.

For shorter ranges, out to 600 yards or so, the shorter barrels shoot accurately and the velocity loss is less important. In a hunting application, the .308 isn't going to take you much further than that, so you can get away with a shorter barrel.

Regardless of barrel length, you are on the right track with a 10 twist, which will let you take advantage of the full range of available bullets.

IMO, maximum versatility and utility in the .308 is obtained in 24" to 26" barrels. If the rifle is going to see more specialized use, longer or shorter than that may be called for.

I agree with all of that. I have a M700 5R 24" that I like a lot and good allround but I chopped a RAR to 18.5" for climbing treestands and such & if strickly long range I would say 26-28" but all round I would lean toward 22-24, but 20" does quite well, no wrong answer just depends on your usage. Here is another article I saw just today: http://bulletin.accurateshooter.com...l-chop-test-how-velocity-changes-with-length/
 
I've had a 20" and a 24" .308 Win. Both shot 1 ragged hole groups. For a strictly hunting rifle under 500 yards, 20" is more than enough tube. For a rifle that will mostly be used for long range and as a target shooter/range toy...24-26" is best.

These are just my opinions based on my own personal experiences.
 
I've had a 20" and a 24" .308 Win. Both shot 1 ragged hole groups. For a strictly hunting rifle under 500 yards, 20" is more than enough tube. For a rifle that will mostly be used for long range and as a target shooter/range toy...24-26" is best.

These are just my opinions based on my own personal experiences.

Hey MudRunner, what are your thoughts on a 1/9 twist 24" MTU for 185-200gr for steel out to 1200yds? Cheap plinker for target? Creedmoor , SAUM and STW are alot more expensive to feed. We wont even get into STW cost. You know that well.
 
Hey MudRunner, what are your thoughts on a 1/9 twist 24" MTU for 185-200gr for steel out to 1200yds? Cheap plinker for target? Creedmoor , SAUM and STW are alot more expensive to feed. We wont even get into STW cost. You know that well.

Bravo 4 is correct. If you really want his opinion, try LRO.

If not, look at some of Montanamarine's old posts, he shot .308s with bullets up 230, 20.5", 1:12" well beyond the 1200 range.
 
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FYI - Ret Marine with an OLD 700BDL 1/10 twist, 23" barrel (yes 23") and a OLD glass beaded stock. It simply adores 178's, though 175's & 180's work almost as well, depending on slug & load. My longest verified hit of a four legged fuzzy creature was 1,374 meters, which was DRT. I had a GREAT spotter, perfect day at almost dead on 1200 noon, clear skies, approximately 375ft elevation, ZERO wind (& I mean ZERO wind). Was feeding it 175GR HPBT M118 LR and between awesome gear, GREAT spotter, a little bit of experience and a Lot of Luck, I made my longest hit... oh yeah, many kudos to bambi for standing still! Of course at that range he felt pretty relaxed and just stood there eating. Just saying, people too readily discount the venerable 7.62, aka .308 and it's ability to reach out & touch. I.E. I worked with a company that made "White Feather" Ammunition (back a few years) and we were able to call it that because we worked it out with Carlos; who's endorsement statement, (that he personally coined after testing the ammo) was "If you're not going to shoot past 1600 meters, don't waste your money!" That was with a 175gr SMK pill. Of course our load tolerances were extremely precise and consistent, so again, do not discount the .308 boys & girls.
 
How was that 175 SMK's terminal performance at subsonic (900-950'ish fps) velocity? Mushroom, yaw, fragment, tumble, pencil through?
We will push 118LR out to 1000 meters just to do it but find them very inconsistent past that, accuracy wise. They don't transition well. This is at around 2600 fps and 11" twist.
 
One more vote for 20" - 22" barrel for the .308. I currently own 4, from 20" up to 26". They are all built for different situations. I strongly prefer a 1-10" twist if heavier bullets will be used, however my 26" target rifle has 1-11" twist and stabilizes 190 grain Berger VLDs to 1,000 yards or more. The rest of my rifles have 1-12" twist which I believe is considered "standard" for the caliber. -Ed
 
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