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Considering a new build AR10

Discussion in 'Rifle Discussion' started by kev350, Dec 10, 2014.

  1. kev350

    kev350 Gresham , Oregon Bronze Supporter Bronze Supporter

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    Hey all I'm getting ready to start a build. Now my question to start is what barrel length it's going to be a long range shooter / hunting rifle? I was was thinking 20" or would 18", 22" be a better choice? Any input is appreciated.

    Thanks
    Kevin
     
  2. Mr Smith

    Mr Smith 54 68 65 20 73 74 69 63 6b 73 Active Member

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    22" will obtain maximum velocity from a .308, but the accuracy difference between a good 18" and 22" barrel will be negligible at best.

    I would go with a 3-groove polygonal rifled barrel though vs a 6-groove. It will last a lot longer, easier to clean, and just as accurate if not more accurate.

    Sub MOA can easily be achieved from a good 18"

    I'm thinking about going with a BHW 18" semi-bull or bull on my .308 build.

    BHW makes barrels for both DPMS and Armalite spec rifles and they are made locally in Oregon out of 416R stainless steel :D
     
    3MTA3 likes this.
  3. kev350

    kev350 Gresham , Oregon Bronze Supporter Bronze Supporter

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    Thanks for the info. I was BHW is only 45 mins from I'll check them out. I was looking at a JP barrel with a matched bolt. I was thinking of using one of their low mass set ups. Any input on this set up I'd like the best bang for my buck. Suggestions welcome.
     
  4. spectra

    spectra The Couve Moderator Staff Member Bronze Supporter

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    Vorpalis and PigNorton91 like this.
  5. Lance Jacobs

    Lance Jacobs South Willamette Valley Oregon Well-Known Member

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    I think that one of those JP barrels would be an excellent choice. Either the 18 or 20 inch would be a good options, in my opinion.

    Those Noveske barrels are really rather heavy. 3 1/2 lbs for the 18 inch model. If you plan to hunt with this rifle, then you don't want to make it real heavy by installing a heavy barrel.

    .
     
  6. Mr Smith

    Mr Smith 54 68 65 20 73 74 69 63 6b 73 Active Member

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    if you want a lighter setup, check out the deals at SAA.

    They sell the lighter BHW barrels for a very reasonable price and they come with a free SAA stripped upper receiver. SAA is based out of Tacoma, WA. However their brick and mortar store and online store offer different deals and different inventory.

    I bought my carbine m4 BHW barrel from them and have their free stripped upper in my AR15. They are very nice uppers, and BHW makes excellent extremely accurate 3-groove polygonal rifled barrels.
     
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  7. kev350

    kev350 Gresham , Oregon Bronze Supporter Bronze Supporter

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    Well my AR 10 build just became an AR 15 build Wilson Combat had a sale on a matched receiver set I couldn't pass up lol. AR 10 on hold for a bit. Now I'm thinking a match grade .223 Wylde for this one. I've never dealt with this chambering any thoughts on this pro's vs con's maybe?
     
  8. Mr Smith

    Mr Smith 54 68 65 20 73 74 69 63 6b 73 Active Member

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    .223 wylde is supposed to be able to run both .223 rem and 5.56x45mm nato, however I have heard rumors that when they get warm they don't cycle 5.56 as well. However those are rumors and I don't have first hand experience with that.

    My M4 barrel is chambered in 5.56x45 nato which can run both .223 and 5.56 reliably.

    my barrell is 1:8 twist and tends to favor heavier rounds. Seems to really like the 62gr M855's

    not that 55gr can't run through it as I have a bunch of it and have run 60rds of 55gr through it already. the 55gr just isn't as accurate as the 62gr at distance with the 1:8 twist. however the 62gr is a tack driver out of that barrel at distance. almost zero drop out to near 500yards. 55gr tends to drop off sooner with my barrel, however that has more to do with the twist rate than the chambering. a 1:7 twist would be better for 55gr and lighter.

    if you plan on shooting more .223 than 5.56 I would go with a 1:7 twist as most .223 is 55gr and lighter.

    5.56 tends to be 55gr to 62gr as the most common bulk round, and 68gr+ for the match grade rounds. avoid 1:9 twist unless you plan to reload or shoot only heavy match grade rounds.


    back to .223 wylde it should hold nice groups with .223 and 5.56 as long as the twist matches up with the bullet weight. 55gr and lower should use 1:7 twist. 62gr+ does better in 1:8 twist

    not to say that 1:7 cant fire 62gr or 1:8 cant fire 55gr cause they can. they just aren't optimal twist rates to stabilize the round for distance shots.

    IMO 3-groove polygonal rifling is one of the best rifling types as it is easy to clean, very accurate, and very wear resistant. Just my opinion. rainier arms and BHW both offer .223 wylde chambered match grade barrels. rainier also offers ultra match barrels. however I think their select barrels are going to be just as accurate.
     
  9. Lance Jacobs

    Lance Jacobs South Willamette Valley Oregon Well-Known Member

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    Mr Smith: What you are reporting here is pretty much the opposite of common convention and wisdom. Certainly opposite of my experience too.

    Longer and heavier bullets need tighter twists to stabilize properly. Lighter bullets tend to work better with the less tight twists. I would dispute the advice that you gave here.


    Kev350: Checkout this article:

    http://www.gunsandammo.com/ammo/pair-barrel-twist-rates-ammo/

    .
     
  10. mjbskwim

    mjbskwim Salmon,Idaho Well-Known Member

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    BHW 20"x1/8 twist,556 chamber, for every weight I have put thru it for the win.
    I can not see how the new fangled 'wylde' chamber can be any more accurate than the above barrel.
     
  11. erslll

    erslll Hermiston OR Active Member

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    That is absolutely backwards. Heavier bullets need a faster twist, lighter bullets need a slower twist. 1:7 is faster than 1:9. A 1:7 barrel is going to work better for 60 grain and heavier. 1:9 will work better with 55 grain. 1:12 would be better for 40 grain.

    You are right though that it isn't hard and fast rule. 40s probably won't shoot well in a 1:7 but 55s might.
     
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  12. Mr. Ben

    Mr. Ben Snohomish Co. Active Member

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    Fantastic barrel: http://www.whiteoakarmament.com/xcart/product.php?productid=17518&cat=312&page=1
     
  13. mjbskwim

    mjbskwim Salmon,Idaho Well-Known Member

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    I have found the 1/8 to be very good for all weights from 55g to 68g. I have used that twist on about 4 AR builds so far with great accuracy results.
    1/7 if I have to and wouldn't use 1/9 unless in a bolt gun just for PD,squirrel hunting.Then there would be a use for 40g bullet
     
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  14. Lance Jacobs

    Lance Jacobs South Willamette Valley Oregon Well-Known Member

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    Barrel length is also a factor that should be considered. If one is working with short 16 inch barrels, then the tighter twist rates have a definite advantage.

    A 1:8 inch twist rate in a 16 inch barrel gives you two full revolutions of the bullet. But go with an 18 inch barrel instead, and a 1:9 inch twist rate will then also still give you two full revolutions too.

    And if one owns a 223 bolt action varmint rifle with a 24 inch barrel, a 1:12 twist rate will give you two full revolutions in that barrel as well.

    .
     
  15. erslll

    erslll Hermiston OR Active Member

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    Your math is correct but I have never seen any thing that proves that it is beneficial to get a certain amount of revolutions for better accuracy.
     
    mjbskwim likes this.
  16. IronMonster

    IronMonster Washington Opinionated Member Diamond Supporter

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    I own 3 .223 Wylde AR's and almost a dozen more in 5.56. The gun I have set up for accuracy is a 20"
    223 Wylde with a 1/8. It will shoot 2 groups at 200 yards with 77gr BTHP's Which honestly is not any better than my 16" Noveske in 5.56. What I have found with the Wylde chambered guns is that any improved accuracy benefit exceeds my shooting ability. If you are shooting precision hand loads at 500 yards you may see the benefit of the .223 Wylde, However normal shooting with good factory ammo I dont think there is enough difference that you could notice.

    As far as twist rates If you ever plan on shooting stuff 55gr and lighter the 1/7 is too fast. (in my opinion) I have had 40gr projectiles disintegrate out of a 1/7 The 1/8 or 1/9 will handle the entire gambit quite well and there are lots of barrel choices. I shoot mostly 62gr stuff but I shoot 77gr BTHP/OTM for long range accuracy. I also sometimes plink and practice with 55gr stuff simply because its cheap. Both the 1/8 and 1/9 have shown they can handle everything from 40gr to 77gr reasonably well. In my mind there is no benefit to the 1/7 as the 1/8 and 1/9 are fast enough for even the 77gr and you dont lose the ability to shoot the lighter stuff like you do with the 1/7 My understanding is the Military chose the 1/7 because of its ability to fire tracers. They are also only shooting 62gr (and rarely 77gr for the squad marksman) and commonly shooting them out of short barrels (14.5") so that fast twist rate is called for. I also read that Colt recommend they go with a 1/8 but some official over ruled that recommendation thinking he knew better
     
  17. mjbskwim

    mjbskwim Salmon,Idaho Well-Known Member

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    Excellent,not sure what for but excellent math
     
  18. Lance Jacobs

    Lance Jacobs South Willamette Valley Oregon Well-Known Member

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    Barrel length has a number of effects. It also has a significant influence on velocity, which is yet another factor to take into consideration.

    No doubt that the short 14.5 inch barrel length on military carbines influenced them greatly in using a 1:7 inch twist with it. And the likelihood of the problem that IronMonster describes with 40 gr bullets breaking apart is also greater when the bullet is going faster in higher velocity loads, and/or in longer barrels. Shoot fast 40 gr ammo in a longer barrel with a tight twist, and that will most definitely be a problem.

    For a varmint hunting AR-15 with a longer 20 or 24 inch barrel, I would thus recommend a 1:9 twist if you want to also be able to shoot 40 gr bullets.

    There is a reason why Hornady's SuperPerformance ultra high velocity 223 load uses a 53 gr bullet, and is not offered in a 40 gr. bullet. Hornady knows that many people are hunting small game with AR's these days, instead of bolt actions. And that a super fast 40 gr load would have major problems in AR-15's with tight twists.

    .
     
  19. mjbskwim

    mjbskwim Salmon,Idaho Well-Known Member

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    No,I get the barrel length part. Never heard the stuff about twist/barrel length .
    I'll have to investigate further cause I'm not seeing how twist will change performance in different length barrels and have never read such.
    This only explains how many complete turns a bullet may get with given twist.