16” or 18” 308 ar barrel

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  • Chazp89

    Active Member
    Sep 1, 2017
    283
    I’ve been sitting on a dpms pattern ar 308 receiver and think I will finally start slapping it together. I’m aiming for something like a dmr, not quite a 1000 yard sub moa gun but still accurate at reasonable distances (Within 300 yard max). Compactness isn’t a goal with this one, I’ll be using a fixed stock.

    Which barrel length would you recommend? Pros cons of both?
     

    Nay_sayer

    ...
    May 30, 2013
    601
    Lothian, MD
    Either one would do 300 yds without a problem. My GII with 16” barrel can hit the 300 yd steel plate at Delmarva with ZQ1, Perfecta or Tula and iron sights and I’m just an average shot.
     

    sajidakh

    Active Member
    Dec 28, 2010
    981
    I feel a difference with the recoil impulse between a 16 and an 18 inch, which is why i went with the 18.
     

    ZeroCool

    Active Member
    Nov 8, 2006
    330
    Glen Burnie
    You know, I was going through this same dilemma with an AR10. I ended up going with a 16" tube because of a killer deal and honestly, it hits plates just as easy as my 24" bolt gun at the distances I shoot (mostly within 200 yards).

    That said, if both were the same price and it was going to be my "do-all" gun, I probably would have gone with 18". I think they look a little better and the extra FPS (even if minimal) doesn't hurt...
     

    BradMacc82

    Ultimate Member
    Industry Partner
    Aug 17, 2011
    26,177
    18", 50fps may not mean much at the shorter ranges you listed, but if you find yourself ever taking shots at mid to long range - that 50fps difference can be the difference between banging the plate or having to come up some.

    **Although in all honesty, unless you're shooting FGMM ammo, you'll probably see a bigger swing in velocity with off the shelf ammo than you would between 16" or 18" barrels.
     

    davsco

    Ultimate Member
    Oct 21, 2010
    8,607
    Loudoun, VA
    I’ve been sitting on a dpms pattern ar 308 receiver and think I will finally start slapping it together. I’m aiming for something like a dmr, not quite a 1000 yard sub moa gun but still accurate at reasonable distances (Within 300 yard max). Compactness isn’t a goal with this one, I’ll be using a fixed stock.

    Which barrel length would you recommend? Pros cons of both?

    you're going to get a higher velocity with the longer barrel. while that really won't affect 'accuracy,' that means you'll have less drop (flatter trajectory) at longer distances and the effects of wind will be lessened a little giving you more cushion on wind calls. especially if size isn't a concern, zero reason to not go longer.
     

    steves1911

    Ultimate Member
    Dec 2, 2011
    3,026
    On a hill in Wv
    Out to 300yds won't be much difference in the real world. The problem I found with the 16" 308 I owned was inconsistent velocity due to incomplete powder burn. My handloads that had an extreme spread In the teens through my bolt gun varied by almost 100fps In the shorter tube. This becomes a big problem In accuracy if you ever intended to stretch it's legs. You will even notice it at 300yds In vertical stringing on paper when shooting groups. The effect can be lessened by experimenting with different load combos but it will never go away and the longer the range the harder it will be to achieve an accurate dope.
     

    DSBartender

    Banned
    BANNED!!!
    Dec 12, 2016
    250
    Waldorf
    Not really a big difference. You gain about 50fps with the 18" barrel. But no noticeable difference in accuracy.

    Here's a good article about .308 and barrel length.

    http://www.thetruthaboutguns.com/20...t-barrel-length-muzzle-velocity-and-accuracy/

    The sweet spot for .308 is supposed to be about 22". But there really are minimal gains with a longer barrel, especially out to 300yds.



    Thanks for the link. I have been considering what barrel length to go with in my AR10 build and this truly helped! I’ll be going with an 18”, now just have to settle one the best manufacturer in the $300-$400 range.


    Sent from my iPhone using Tapatalk
     

    Chazp89

    Active Member
    Sep 1, 2017
    283
    Thanks y’all! Lots of good advice! I’m thinking I’ll do 18”, I like the idea of the little extra velocity in case I want to reach out a little further at some point. Plus for some reason a 16” barrel on a .308 ar looks a little odd proportionally in my eyes. I was looking at 16” mainly because they seem to run a little less expensive
     

    DaemonAssassin

    Why should we Free BSD?
    Jun 14, 2012
    23,970
    Political refugee in WV
    Thanks for the link. I have been considering what barrel length to go with in my AR10 build and this truly helped! I’ll be going with an 18”, now just have to settle one the best manufacturer in the $300-$400 range.


    Sent from my iPhone using Tapatalk

    Thanks y’all! Lots of good advice! I’m thinking I’ll do 18”, I like the idea of the little extra velocity in case I want to reach out a little further at some point. Plus for some reason a 16” barrel on a .308 ar looks a little odd proportionally in my eyes. I was looking at 16” mainly because they seem to run a little less expensive

    Go with a Criterion barrel. Right around 350 at Brownell's.
     

    firemn260

    Active Member
    Sep 15, 2015
    354
    Harford County
    I went with a JP 18” barrel for my build. I wanted a rifle length gas system and JP offers it in the 18 and up barrels. Also in my opinion it looks better sticking out of a 12” handgaurd.

    I realize JP is a little pricey but I couldn’t be happier with how mine shoots.
     

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