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View Full Version : Best use of and barrel length for a 308 AR?


GunOwner
10-04-2009, 3:52 PM
I am building a 308 AR (AR-10) and I am trying to decide on barrel length. I know your first question will be depends on the purpose so first tell me what you think the best use of a 308 AR is.

My assumption (subject to your collective wisdom) is that a regular AR-15 is fine for close in work or inside a building where a short barrel is key. So I am thinking the AR-10 will be best for longer range shots. I think typical barrel twist is 1:10 so I am thinking 16" barrel is not ideal to stabilize the round - should I go 20" or 24"?

p.s. I have seen Saiga 308s with 16" barrels fired and WOW what a flame thrower.

Flying Bones
10-04-2009, 4:49 PM
Good question. TAG for the someday build.

Hoop
10-04-2009, 4:54 PM
When they tested the 18" barreled dpms one they got sub moa out of it (it's an 18" bull though). I would say 20" is the best balance since any longer and it will start to get heavy, while only giving a small increase in velocity you won't notice until you shoot really, really far.

edit:

this article might help you:

http://www.snipersparadise.com/tsmag/march_2000.htm

jmf_tracy
10-04-2009, 4:54 PM
i chose other because i like my 22" 1:11 twist GAP upper. it is a long range tactical rifle for 100-1000 yards. 20" is probably a good compromise unless you plan on going out to 1000 yards then 22" would serve you better.

GunOwner
10-04-2009, 8:23 PM
Thanks

C.G.
10-04-2009, 9:01 PM
i chose other because i like my 22" 1:11 twist GAP upper. it is a long range tactical rifle for 100-1000 yards. 20" is probably a good compromise unless you plan on going out to 1000 yards then 22" would serve you better.

+1. When I'll have the money I'll get a Krieger 18" and 22" barrel for my two lonely upper receivers, but as mentioned 20" would be a good compromise if you only want one.

technique
10-04-2009, 9:42 PM
10.5 - 11.5in :43:

Jpach
10-04-2009, 10:15 PM
+1. When I'll have the money I'll get a Krieger 18" and 22" barrel for my two lonely upper receivers, but as mentioned 20" would be a good compromise if you only want one.

Amen to that Brotha. I read this article, http://www.tacticaloperations.com/SWATbarrel/ , and pretty much gathered that with the custom barrels (does Krieger count as custom? parhaps I'll go Bartlein) will generally run faster velocities at all lengths in comparison to non-custom production barrels. If the guy in the video below can still kick *** at 1K with an 18" .308, then an 18" .308 AR should be an awesome gun to have.

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ar15barrels
10-04-2009, 10:35 PM
Amen to that Brotha. I read this article, http://www.tacticaloperations.com/SWATbarrel/ , and pretty much gathered that with the custom barrels (does Krieger count as custom? parhaps I'll go Bartlein) will generally run faster velocities at all lengths in comparison to non-custom production barrels. If the guy in the video below can still kick *** at 1K with an 18" .308, then an 18" .308 AR should be an awesome gun to have.

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Two things about that video...
First, it's a tight bore barrel.
The krieger barrels you see being sold for 308 AR's are usually NOT tight bore barrels.
Second, the 18" barrel in the video is a running a can.
The can adds velocity almost equal to the length of the can so that 18" is performing more like a 22" barrel.

swerv512
10-05-2009, 3:49 AM
if you want a tack dirver, get a 24" 1:10 barrel. it's only heavy until you put it down and shoot....

DirtRacer151
10-05-2009, 7:37 AM
if you want a tack dirver, get a 24" 1:10 barrel. it's only heavy until you put it down and shoot....

lol i like that

Jpach
10-05-2009, 1:09 PM
Two things about that video...
First, it's a tight bore barrel.
The krieger barrels you see being sold for 308 AR's are usually NOT tight bore barrels.
Second, the 18" barrel in the video is a running a can.
The can adds velocity almost equal to the length of the can so that 18" is performing more like a 22" barrel.

Blast, ther always has to be a catch. Would it even be wise to run a tight bore on a .308 AR? Are there cons in the reliability department?

Are you sure the cans would boost that much velocity? I read this thread on the hide http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1168563 and people arent really experiencing the same velocity boosts you describe. It even has an alleged quote by Surefire that pretty much says that velocity increases are in the range of 30-50 fps.

ar15barrels
10-05-2009, 1:13 PM
Blast, ther always has to be a catch. Would it even be wise to run a tight bore on a .308 AR? Are there cons in the reliability department?

Are you sure the cans would boost that much velocity? I read this thread on the hide http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1168563 and people arent really experiencing the same velocity boosts you describe. It even has an alleged quote by Surefire that pretty much says that velocity increases are in the range of 30-50 fps.

Tight bores increase pressures.
That's HOW they make more velocity.
As long as you keep your pressures under control (short barreled shooters usually don't because they are chasing velocity), there's really no reason not to run a tight bore on an AR-10.
Just KNOW exactly what you are getting into before you go there.
It's going to be a gun for handloads only.

The general rule on suppressors is that they give you half the velocity that the additional barrel length would.
So if you have an 8" of can forward of the muzzle on an 18" barrel, it's like shooting a 22" barrel.
Put that can on a tight bore barrel and it's almost like shooting a 26" barrel with the extra pressure of the tight bore.

There's no free lunch.
If you believe that there is, you are foolish.

Jpach
10-05-2009, 1:30 PM
The general rule on suppressors is that they give you half the velocity that the additional barrel length would.
So if you have an 8" of can forward of the muzzle on an 18" barrel, it's like shooting a 22" barrel.
Put that can on a tight bore barrel and it's almost like shooting a 26" barrel with the extra pressure of the tight bore.

There's no free lunch.
If you believe that there is, you are foolish.

Jesus, cans are the **** then. It seems silly to not run them if you are in a free state.