If you were rebarrling an AR?

Discussion in 'Large-Bore/Small-Bore Rifle/Shotgun' started by lonewolf204, Aug 18, 2012.

  1. lonewolf204

    lonewolf204 Well-Known Member

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    If you were going to rebarrel an AR 15 5.56 what barrel would you use? What manfacture, what twist, what length of barrel, and what barrel contour would you use and why? Sub MOA is what I'm looking for and can't seem to get it with what I have. I would like to here your ideas on the subject. Thanks in advance.
  2. Ledslnger

    Ledslnger New Member

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    I would keep my old 5.56 barrel in the corner and get a new barrel in .300 Blackout. Same magazines & bolt and I would be good to go.

    Wilson Combat for the brand.
  3. cpttango30

    cpttango30 Guest

  4. aa1911

    aa1911 Active Member

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    blackout is what I'm wanting also, very easy to do and it's a fun cartridge. It's on my list of AR uppers to build next.

    Kreiger makes fantastic barrels, Douglas made some fantastic match grade barrels a while back but have not checked them out recently. Most of the hi-pwr guys using AR's seemed to prefer a Douglas years ago. I'll have to look around and see who's still out there for match grade stuff. Most manufacturers should be able to get you MOA at least though.

    I would do a 1:7 or 1:8, either will work good with most bullets. someone figured out with the standard match ammo, a 1:7.76" twist was optimum; how they came up with that is beyond me...
  5. LDBennett

    LDBennett Well-Known Member

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    lonewolf204:

    It really depends on your intended usage: tactical, plinking, varmint or ?. also what caliber you intend to use.

    The Varmint guns need a longer heavy barrel. The tactical shorter, lighter barrels. The fast twist barrels are better for the longer heavier bullets and sometimes do not shoot classical 55 gr 223 bullets very accurately at all. The slow twist barrels don't stabilize the longer heavier bullet all that well and accuracy suffers.

    The suggest Krieger barrels are good. My Varmint AR15 has a Lothar Walther barrel which performs excellently. Brownells sell barrels at several price points and you get what you pay for in barrels.

    Changing a barrel on the AR platform is easy if you buy one with the barrel extension (where the bolt engages) already installed. That takes care of head spacing for standard parts. It requires torquing and if you choose to change the barrel out I suggest the AGI video on building your own AR for details.

    LDBennett
  6. lonewolf204

    lonewolf204 Well-Known Member

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    Thanks aa1911 and LDBennett your input is greatly appreciated and very helpful.
  7. lonewolf204

    lonewolf204 Well-Known Member

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    I just want an accurate AR 15! To me 3" groups @ 100 yards is not very accurate. I was thinking about trying the 223 wylde. I don't want a rifle that is to heavy to carry hunting. Everything I read about 223 Wylde sounds good. But would like some more opinions before I spend the money.
  8. lonewolf204

    lonewolf204 Well-Known Member

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  9. GunHugger

    GunHugger Well-Known Member

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    What manufacture?

    There are many that make good accurate barrels. Since I have no idea as to how much money you are willing to throw at "sub moa" I'll have to let you pick.

    Here's a few links to some good ones.
    Shilen http://www.shilen.com/ar15Barrels.html
    Krieger http://www.kriegerbarrels.com/DCM__AR_15-c1246-wp3394.htm
    Lilja http://www.riflebarrels.com/products/ar.htm
    White Oak http://www.whiteoakarmament.com/xcart/home.php?cat=250

    What twist?

    I'm not a big fan of 1 in 7 unless you plan on shooting bullets heavier than 69 gr.. I like 1 in 8 for what you are wanting. BUT it depends on what bullet weight and shape you plan on shooting. Heavy and/or long bullets will shoot better out of a tighter twist such as 1 in 8 or 1 in 7 lighter shorter bullets like less twist like a 1 in 9 or 1 in 10. This is a subject that has been discussed over and over and still many people will argue as to which is best. I like 1 in 8 for a good compromise since it will handle the heavier bullets and still do just fine with 55 gr too.
    Basically it's....
    1 Turn in 7” ------------ 77 grains Max
    1 Turn in 8” ------------ 69 grains Max
    1 Turn in 9” ------------ 65 grains Max

    What barrel length? (didn't we cover this in your other thread?)

    As I said there, I think 20" is more than long enough, but some will say to go with a 24"...I'm not one of them unless you want to shoot at long ranges like 300 yards or more since you will gain a little velocity.

    What barrel contour would you use and why?


    I can't answer that with the info I have. A carry around hunting gun...I would want a 24" bull barrel due to weight. A range only gun is a different matter.


    You didn't ask about which chamber. For accuracy only go with a 223 chamber and stick with quality 223 target ammo or well made hand loads.

    If you plan on shooting military type 5.56 ammo too then go with a Wylde type chamber than does a good job at handling both 223 and 5.56. But there's always a compromise and it might not be as accurate as a 223 chamber.

    And you do not want a chrome lined bore.

    And you will want to free float the barrel.
  10. LDBennett

    LDBennett Well-Known Member

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    lonewolf204:

    As to twist rate, you use the Greenhill formula to find the heaviest longest bullet a barrel twist will support. The key element in stability is not the weight of the bullet but the length for a particular diameter. But there is a down side to too fast of a twist.

    The implication is that you can not have too fast of a twist. That is not right practically. I have a AR with a barrel with a 1 in 7.5 inches in 223 which shoots the heavier bullet just fine. But my old standby 55 grainners (a hunting bullet chosen by chance years ago) did not like the fast twist at all. The fast twist over spun that bullet and they actually disintegrated before reaching the target. Slowing the velocity down (which reduces the spin rate) and moving to a varmint bullet allows me to shoot those lighter shorter bullets but the accuracy is not there. The best accuracy was with the heavier longer bullets.

    You know there may be more accuracy in your old barrel. If you free float it, re-crown it, find the bullet, and load that it likes it might do better than 3 inch groups at 100 yds. Just changing to a different cartridge and barrel is no guarantee of better accuracy.The quality of the barrel is important but so is all the other details listed above. My guess is if you just change the barrel and cartridge without doing the other things suggested, and do no real load development you will not get any better accuracy and be disappointed. You need to wring out what you have first before moving to a different barrel and cartridge. There is no magic cartridge. Hard work on the gun and your shooting technique, and the reloading is what gets you better accuracy. Yes, a bad barrel can not be saved but is your barrel bad or just not pushed to its limits of accuracy by you?

    I have sold guns because the barrel was not good but I proved to myself that was the case before they left me.



    LDBennett
  11. GunHugger

    GunHugger Well-Known Member

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    Good advice from LD above.

    As to 1 in 7 twist rate barrels and why we have them is an interesting story.

    I may have posted this here in the past but it's worth posting one more time for those that haven't read about it.

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

    Below is information from the owner, Ret. Lt. Col. Mark Westrom on the subject.

    The Facts Behind the 1:7 inch twist AR barrel

    There's a lot of buzz around that the 7 inch twist barrel is just the thing for the AR family and that a 1:9 inch twist barrel is second rate.

    This isn't actually true, and ArmaLite's President, Mark Westrom, was deeply involved with the matter while a Civil Servant at the Armament Command at Rock Island. It's an interesting story.

    In the early days of the M16A2 he received a message that Procurement was set to buy 155,000 M16A1 barrels just when the Army was switching to 1:7 inch M16A2 barrels. The problem wasn't merely poor accuracy or logistics; he was concerned that because the 1:12 inch twist barrels wouldn't stabilize the M855 well enough to prevent wounds that were likely to raise Geneva Convention complaints, it would make both legal and logistic sense to settle for a compromise barrel that would handle both.

    He consulted with Col. (Dr.) Marty Fackler, he of the Army's Wound Ballistics Laboratory, who agreed with him and offered to run some pig cadaver tests to verify if a problem existed. Westrom sent the proper request and Fackler confirmed that use of the M855/865 bullets in the 1:12 inch twist left dramatic but somewhat less than effective wounds.

    Westrom consulted with ammunition specialists at Picatinny Arsenal and proposed that even though 1:7 was required "to stabilize the M856 tracer" the 1:9 inch twist rate should be fine for both M193 and M855 ball rounds and would be good enough for the usual purposes of tracers: close in fire at night. He was surprised when he was told "No, 1:9 is actually pretty much optimal for the M856 tracer. 8.5" twist actually."

    Upon further questioning he was told that 1:7 was used in the M16A2 because it was used in the M249 Squad Automatic Weapon. FN submitted the M249 with 1:7 inch twist and it won the SAW competition and was thus produced with that barrel. They didn't know why 1:7 was used in the M249. (It over stabilized those bullets, which led to decreased long- range accuracy and reduced barrel life.)

    Westrom asked the authorities to call FN to find out why they used the odd 1:7 inch rate.

    The next day Picatinny called back and said "You aren't going to believe this: FN remembered the accusations the US received over the cruelty of the early 1:14 inch rifling twist of the early M16." They used 1:7 inch twist so they'd never have to answer that complaint.

    In other words, the 1:7 inch rifling twist was a political decision of a Belgian civilian, not a technical decision at all. As one foot follows the other, we've gone forward with the odd barrel.

    So here's where we are today. 1:9 is great for M193 bullets and to around 70 grains. 8 inch twist is fine for bullets up to around 77 grains. Higher twist rates are sometimes used for even heavier bullets.

    But these bullets aren't those used outside competitive shooting, and normally loaded one shot at a time. Some military ammunition uses a 77 brain bullet, but that's rare with commercial arms and is VERY hard on the bolt of the M16.

    ArmaLite does make rifles with 1:7 inch twist for those contracts that require it, but for almost all military, police, and civilian use it's suboptimal.

    Our customers learned this early on. Years ago ArmaLite sold 1:7 inch twist barrels and the market very much disliked them. It took a long time to sell them. The idea of a chrome-lined 1:7 inch barrel for match-type isn't very logical, but we'll build them when the customer demands.

    The bottom line is though, that sometimes what the customer wants is driven by funny advertisements rather than technical facts. This isn't the only issue that falls into that area.

    Westrom's idea is that DOD should switch to the 1:9 inch barrel for both the a1 and A2 rifles? He was allowed to convene a meeting on the topic that stunned him. He was savaged for the idea. And this was by friends. He raises the issue later when another 120,000 1:12 inch barrels were being bought, to the same end.

    But one of his first actions at ArmaLite was to standardize the flexible 1:9 inch rate.
    Last edited: Aug 20, 2012
  12. lonewolf204

    lonewolf204 Well-Known Member

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    Thanks LD and GunHugger! Those 3 replies make alot of sence to me. That is exactly the input that I needed. Thank you!
  13. Twicepop

    Twicepop Well-Known Member

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    If your thinking alternative calibers, put the 6.5 Grendel or the 6.8 SPC in there also. Both of these fit in the standard AR platform also.

    those who beat their guns into plowshares, will plow for those who didn't
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