.308 barrel length?


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MovedWest
October 18, 2009, 10:00 PM
If the barrel quality was constant, what barrel lengths for an LR-308 configuration would you consider the the most versatile? At what point will a longer barrel no longer have affect on accuracy (how long is long enough)?

Also what would you choose for hunting large game (deer, elk) up to 600yds? Suggested rate of twist? Bullet weight would probably be around 160gr.

-MW

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Zak Smith
October 18, 2009, 10:21 PM
To be strict, incremental additional velocity will aid long-range effective accuracy due to less wind drift and more ranging margin of error. Thus, there is no technical point a barrel is too long to have no effect on accuracy, other than when it's so long that it actually slows down the bullet (somewhere way past 30").

I recently wrote this about 308 and barrel length
At the 2008 Steel Safari, we had a former USMC sniper and very
good rifle shooter using an 18" .308 (the DARPA XM-3) shooting
mil-spec 175gr match ammo. I would rate his skills amongst the top
5 shooters at the match. He came in 15th. The best .308 shooter
was using an approx 24" barrel firing the 155 Lapua Scenar at over
2925 fps. I would also rate him amongst the top five shooters for
skill. He came in 7th. The top 10 places were dominated by 6.5 mm
and 7 mm cartridges.

If you really intend to shoot at long range, then a longer barrel is better than short. Also, if you really intend to shoot at long range, there are much better cartridge choices than .308.

For a .308 I would shoot at long range, ever, I personally wouldn't go shorter than about 22".

Also note that the best long-range bullets are probably not the same bullets you want to use to shoot very large game.

-z

dubbleA
October 18, 2009, 10:24 PM
If the barrel quality was constant, what barrel lengths for an LR-308 configuration would you consider the the most versatile? I would chose 20 inches. At what point will a longer barrel no longer have affect on accuracy (how long is long enough)? There are some variables here, barrel contour is a factor. The heavier the contour, the longer the barrel can be without excessive barrel whip.

Also what would you choose for hunting large game (deer, elk) up to 600yds?If you really plan on ranges of 600yds, I would'nt consider a 308 Win, it' s a great cartridge but simply doent have the steam at 600yds. The 30 cal mags shine.... examples are 300WSM, 300 Win and WBY. Suggested rate of twist? a 1:10 or 1:12 depending on what bullet is used. Bullet weight would probably be around 160gr.168 ish will do for the 308Win while in a magnum a heavier bullet such as 180-208 grs will work fine.

Of course there are many opinions out here and this one is mine so your milage will vary.

MovedWest
October 18, 2009, 10:51 PM
Thanks for the responses so far. This was one tidbit I was thinking about, but couldn't come up with the words for it:

Also, if you really intend to shoot at long range, there are much better cartridge choices than .308.

I totally agree. For longer range stuff I'm planning on a 7mm Rem Mag in bolt action. The .308 I'm building right now is meant to fit the gap between my 5.56 AR and the future 7mm RM. I was at the range two weeks ago and there was a fellow nailing 3-shot groups @ 200yds with a 300 magnum that could be covered with a silver dollar. It was definitely a firebreather. Does that sound like a 300WSM?

What do you think the maximum effective range of a .308 with a decent 20" barrel?

-MW

pdd614
October 18, 2009, 11:06 PM
depends on your definition of effective range. If we are just talking about ringing steel, then 1k is not going to be a problem. I believe lots of trigger time will overcome the shortcomings of your barrel.

blackops
October 18, 2009, 11:36 PM
Zach pretty much covered it, definitely at least 22 inch barrel. I would go with a 22 if you want to hunt. It will still give you the velocity and be manageable to carry. Put a 1:12 twist on it. I would suggest Krieger as well as far as barrels go. The bullet for hunting I prefer is the Barnes Triple Shock, for a 308 168Gr.

MovedWest
October 19, 2009, 12:51 AM
Cool - thanks for the info guys! :)

H2O MAN
October 19, 2009, 08:06 AM
On the other hand... 18.50" barrels seem to be more than adequate (http://www.deathfromafar.com/htm/08_iba_weaponsys_xm3.shtml).

http://www.deathfromafar.com/images/DSC_0761.jpg


I don't know a thing about this rifle, but I did find the web page interesting.

pdd614
October 19, 2009, 08:19 AM
that xm-3 is a joke. 8,300 dollars could just about buy you a aiaw with a premier or schmidt bender scope. it doesn't even have a detachable mag assembly or adjustable check piece. i'm not knocking the barrel length, just the price tag. maybe the xm-3 has some magic pixie dust stored away in the cheek riser pouch to justify the price. I sure hope so.

H2O MAN
October 19, 2009, 08:21 AM
Agreed, the prices are insane.

DRYHUMOR
October 19, 2009, 08:43 AM
In my mind, nothing more than instinct, I always thought that to have 2 complete revolutions of the projectile was most desireable. IE 1:10 20 inches, 1:12 24 inches. Kind of works out to roughly 2 revolutions or better per barrel length, based on twist.

I have spoken to smith's before that did the same thing that most do on occasion- take a barrel and cut off an inch at a time, re crown, and shoot/evaluate. The heavy contour maintains stability longer, all barrels have a "sweet spot" in length that works well for the load/ammo being used. The disadvantage of cutting- once you pass the sweet spot, you need a new barrel.

Any thoughts?

Zak Smith
October 19, 2009, 12:14 PM
Did you read my post about the XM-3 at the '08 Steel Safari? In the hands of a very talented shooter, it wasn't awesome.

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