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Old March 19, 2015, 05:08 PM   #1
SCHunter90
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Who makes the longest barrel for AR-10

I am selecting all the parts for my build before purchasing them. I am looking to build a .308 AR that is as accurate as possible. I am trying to find a barrel out there that is atleast 26" with a 1:7 twist ratio and preferably fluted. Does anybody know a company or somebody who makes a barrel like this or one even longer?

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Old March 19, 2015, 05:23 PM   #2
Bart B.
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Kreiger makes barrels up to 36" long.

Why do you want a 1:7 twist? What bullets do you want that twist for?

240 and 250 grain 30 caliberSierra HPMK's only need a 1:8 twist for their weight and length in 308's.

Best accuracy happens when the twist is just fast enough to keep bullet long axis parallel to the trajectory. A 1:10 twist in .308's will do good with 200 and 210 grain bullets. Maybe a 1:9 with 220's.

And fluted barrels are typically not as accurate as those without them. Flutes tend to hurt accuracy, because they put another stress issue in the barrel, but Kreiger will flute one before it's rifled if that's what you want.

Last edited by Bart B.; March 19, 2015 at 05:56 PM.
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Old March 19, 2015, 06:05 PM   #3
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And fluted barrels are typically not as accurate as those without them. Flutes tend to hurt accuracy, because they put another stress issue in the barrel
I sure would like to see some documentation on that subject other than gun forum opinions.

I had a QPC/Bushmaster 5.56 A2 20" fluted HBAR 20+ years ago that shot MOA or better at 100 yards with A2 irons on a rest. Bushmaster claimed then that the barrel was MORE rigid and more accurate with the flutes than the standard HBAR. The (more expensive) fluted barrels were offered for many years and if your claim was the case, I'm sure there would have been a bit of backlash and lack of sales.

Just my $.02 worth...
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Old March 19, 2015, 06:28 PM   #4
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Krieger, Hart ,lilja and many others will make you a barrel almost any way you want it. The question is why such a long barrel on a 308? After 26" you gain almost nothing with that caliber and as mentioned above a 7 twist 308 is awfully fast. What bullet do you plan to shoot? In an ar unless you single load the 200gr plus 30 cal bullets are really gonna eat into case capacity if seating to mag length.
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Old March 19, 2015, 06:57 PM   #5
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AKexpat, fluted barrels are rarely, if ever seen on match winning and record setting rifles. Air gauge a barrel before and after it's fluted and you will see the difference.

Besides, fluting one makes it less stiff.
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Old March 19, 2015, 07:05 PM   #6
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more susceptible to hot/cold variance as well if I'm not mistaken.
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Old March 19, 2015, 07:22 PM   #7
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I sure would like to see some documentation on that subject other than gun forum opinions.

I had a QPC/Bushmaster 5.56 A2 20" fluted HBAR 20+ years ago that shot MOA or better at 100 yards with A2 irons on a rest. Bushmaster claimed then that the barrel was MORE rigid and more accurate with the flutes than the standard HBAR. The (more expensive) fluted barrels were offered for many years and if your claim was the case, I'm sure there would have been a bit of backlash and lack of sales.

Just my $.02 worth...
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Bushmaster are 1) not accuracy experts in the slightest. 2) a gun company will make all sorts of claims, with no real proof to back it up.

I used to get to meet with all the major gun companies reps one or two times a year for my job... and you should hear all the claims they make... specially Taurus, its laughable.

Fluted barrels cost more money because its more time and labor. You're paying someone to mill the flutes into the barrel. Most bench and competition shooters like Bart B will point out, its an accuracy issue.

Flutes do a few things.... mostly they are for looks. Secondly long range hunters who hike like to squeeze out any extra ounces they don't think they need... because ounces add up to pounds, and the also allow more surface area to allow the barrel to cool down faster. Weather cooling a barrel down quickly is important to you or not, or even how effect a few flutes are, is always up to debate.

Now, fluted barrels can be pretty DARN accurate that is not what anyone is saying... however Bart is strictly talking about absolute BEST accuracy like in competition when millimeters make a big difference in your ranking.
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Old March 19, 2015, 07:50 PM   #8
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bacardisteve,

Thanks I looked those companies up online and they have exactly what I need.
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Old March 20, 2015, 08:24 AM   #9
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As far as twist rate I am now leaning more towards as fast as a rate as I can get. Look up Todd Hodnett of Accuracy 1st h he has done some research on this and he then followed up with an excellent write up on his findings a couple of years ago. One of the test barrels he used had a 1:2 twist, I don’t remember off the top of my head if that one was chambered in 338LM or 308, regardless, his findings are interesting and the article is worth the read.
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Old March 20, 2015, 08:52 AM   #10
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Quote:
I sure would like to see some documentation on that subject other than gun forum opinions.
I offer no documentation, but offer the following exercise.

Imagine your fluted barrel. Its stiffness is x.

Now imagine that your fluted barrel receives additional bracing with stiff metal adhering to each flute and filling each trough completely.

Would the stiffness of the barrel now be greater than X or less than X?

For a given barrel weight, I could see the fluted version as stiffer, but that would pertain to the outside diameter of the bbl.
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Old March 20, 2015, 09:53 AM   #11
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Quote:
Who makes the longest barrel for AR-15

--------------------------------------------------------------------------------

I am selecting all the parts for my build before purchasing them. I am looking to build a .308 AR that is as accurate as possible. I am trying to find a barrel out there that is atleast 26" with a 1:7 twist ratio and preferably fluted. Does anybody know a company or somebody who makes a barrel like this or one even longer?
Are you sure this is actually what you want, or is there some typos here?
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Old March 20, 2015, 10:03 AM   #12
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DPI7800,

I can't find anything with Todd Hodnett, with a 1:2 twist. Can you send me a link?
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Old March 20, 2015, 10:26 AM   #13
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I think zuki is on to something

and flutes helps dissipate heat faster
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Old March 20, 2015, 10:46 AM   #14
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More gains can be had thru proper ammunition selection and loading, the chamber, leade, and rifling, plus having the barrel tuned and terminated where the muzzle is at it's lowest node of vibration.

That means it very well may shoot more accurately at 18" than 26". There is NO guarantee, what barrel makers try to do it exploit all the best characteristics to get the highest accuracy possible with a specific combination.

Fluting isn't necessarily a best option, neither is additional fps from higher muzzle velocities. There are too many other variables to sort out with bullets, seating depth, neck concentricity, getting the projectile coaxial, neck tension, flame propagation, etc etc etc.

Fluting is highly debatable, it may or may not increase stiffness, aid in cooling or increase accuracy. What I'm seeing lately is a trend to longer barrels with fluting, but no real science to back up any claims. It seemingly has more substance with building a show rifle than a dedicated precision build.

A trip to a competitive event focusing on that class of rifle would be more informative about what real long distance precision shooters are using. If I was seeing the top 25 shooters using fluted 26" barrels I'd pay attention.

Are they?

ps an AR in .308 would be an AR10 - not 15.
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Old March 20, 2015, 01:59 PM   #15
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A 1:2 twist? Please tell me you meant 1:12. A 2 twist is just absurd.
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Old March 20, 2015, 02:31 PM   #16
Bart B.
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Fluting is highly debatable, it may or may not increase stiffness
It always reduces stiffness; fluting removes metal that helped it be as stiff as it was before those strips of metal were removed.

A patio deck with all 2x8's stacked on edge next to each other is stiffer than if every other one was a 2x4.

Fluting mostly misunderstood. It's really simple grade school mechanics.

Imagine 12 pie shaped wedges stacked together in a circle ; pointy end in the middle. Now shorten the wide end half it's length for every other one; you've "fluted" them. When was it stiffer, before the wedges were shortened or after? How much material is their in all axes to resist bending for each condition?
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Old March 20, 2015, 02:51 PM   #17
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Old March 20, 2015, 03:00 PM   #18
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I had no intention of putting a dog in this fight but here goes.
One of my AR’s I built I used a 20 in SS Yankee Hill fluted bull barrel 1:8 twist.
The fluting is shallow scallops that increase surface area for cooling.
This rifle shoots sub MOA out to 300 yds with any ammo I put down it.
I can run it hard and fast and still shoot MOA with any ammo.
Does the fluting affect accuracy?
Does not seem too with this particular barrel design.
There are different styles and types of fluting and just as many barrel designs.
So to make a blanket statement that fluting is bad is not fare statement.
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Old March 20, 2015, 03:25 PM   #19
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I suggest a custom made Kreiger 22" heavy barrel, length works well for a M1A. A 26" barrel works well for a Remington bolt action Sendero or .308 Police. Fulton Armory has a 20" Kreiger and a 24" Criterion, 4.25 lbs. Below may help with twist rates and flutes...
http://www.riflebarrels.com/faq_lilj...tm#twist rates

http://www.riflebarrels.com/faq_lilj...els.htm#stress

Last edited by JohnInLa; March 20, 2015 at 04:21 PM.
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Old March 20, 2015, 04:10 PM   #20
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I think you'll have trouble finding bullets that will hold up to a 7 twist, especially in a super long barrel where your increasing velocity to it's maximum. I think 1:8 may even be too much for most. I would like a 1:8 if using a 16-18" barrel and felt I needed to extra stability to make up for decreased velocity. if your wanting a 26-30" barrel or whatever, I think for popular match bullet choices, you would be best suited with a 1:9 twist. but you haven't said what type of bullets you are planning to shoot, but you are really limiting yourself to only the heaviest available, whether they are inherently the most accurate long range bullet, being the only long range bullet you'll be able to use in your rifle.

lilja precision rifles recommends a 1:10 for bullet weights 240-250gr in .308. I can't imagine what kind of monsters your going to find that are going to be best suited for a 26" 1;7, it sounds ludicrous. I have never heard of this method/theory/combination from any top manufacturers. but if you are willing to do the experimentation....PLEASE let us know if we have been doing it wrong all these years. maybe your on to something, maybe your going to create a mess for yourself.

everything I have read about making a truly accurate target rifle, which isn't much BTW(I am no professional of anything), pick the slowest twist rate which will fully stabilize your chosen bullet. a faster twist rate increases lateral throwoff and aerodynamic jump, the faster the twist, the more deviation from in-bore tipping or bullet imbalance. your call, but they don't make "perfect" bullets, and spinning them that fast at that velocity will exaggerate any imperfections.

I was under the impression that the general "desire" for 1:7 .308 barrels was for sub-sonic shooting, to make up for the loss of stability due to lower velocity

I could be totally wrong about everything I just said, I like fast twists as well, I have been looking for a 1:6 for .223 which people think is silly. i am sure you could find some very accurate loads for the barrel in question, but i think you are really going to be boxing yourself in on choices because they aren't making bullets to your intended specifications.
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Old March 20, 2015, 04:44 PM   #21
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@ bacardisteve
Quote:
A 1:2 twist? Please tell me you meant 1:12. A 2 twist is just absurd.
That was the point they were going for, they were going to a very far extreme to test twist rates. However I may have been off it may have been a 1:4 on the 338. Ill check and get back to you.
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Old March 20, 2015, 07:11 PM   #22
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"ps an AR in .308 would be an AR10 - not 15."

Wrong...

It is an AR-10 ONLY IF made by ArmaLite!

Any other brand of "AR-10 TYPE" rifle is NOT an AR-10...

That is why ALL other makers call their rifles something else, AR-308, LAR-8, SR-762, SR-25, etc...

Come on, learn the difference! It really isn't that hard...

Insisting on calling all brands of AR .308W rifles "AR-10" is (to be kind) as silly as calling all bolt action rifles Winchester 70's whether they are Rem 700's, Rgr 77"s etc...

T.

Last edited by TimW77; March 23, 2015 at 11:29 PM.
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Old March 21, 2015, 07:53 AM   #23
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ps an AR in .308 would be an AR10 - not 15.
------------------------------------------------------------------
Wrong...
LOL, not completely wrong but not completely right. An AR in .308 certainly isn't an AR15 and by name one certainly is an AR10. They are basically AR10 pattern guns.

Come on, learn how to learn to use the quote function when replying. It isn't that hard.
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Old March 21, 2015, 02:37 PM   #24
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Seriously, Tim?

You certainly are factually correct.... BUT, pretty much all discussions both on this board as well as in real life consider the .308-sized AR patterned rifles AR-10 class...

We could then get into how anything outside an Armalite chambered in 5.56 is NOT an AR-15....

But let's not major in the minors...
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Old March 21, 2015, 04:01 PM   #25
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Bart's correct about fluting...always reduces stiffness. Of course, the science exists. Simple h.s. physics.
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