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What You Need to Know About .308 Rifle Builds

Discussion in 'Genesis CNC' started by Genesis CNC, Oct 18, 2015.

  1. Genesis CNC

    Genesis CNC New Member

    Sep 3, 2013
    When it comes to home building a .308 rifle, there’s a lot of information out there to digest. The internet is a wonderful place with an abundance of information, but among that information, there’s also an overload of useless junk that can make it hard to find what you’re looking for. Over the next few weeks, we’re going to help you cut through all that fluff. In this post, we’ll go over some of the basics of compatibility without getting too in-depth. Use these posts as a resource to help you get through your first AR 10 build, and don’t forget stop by our forum for a little extra help.

    An AR-10 Is Not Like an AR-15
    Say “AR” and the automatic response is “15” – but the AR-15 is actually a scaled down replica of the AR-10. With that in mind, you’d think an AR 10 build would be pretty much the same thing, right? It’s true that if you’ve built an AR-15, you shouldn’t have any trouble with its bigger, beefier counterpart, but they’re not exactly the same.

    Most notably, the difference is a matter of compatibility: while the AR-15 has been adopted by the government and parts have been standardized so that a part from any manufacturer should fit into any build, .308 rifle components have NOT been standardized, meaning you’ll have to be conscious of parts compatibility.The power, accuracy, and flexibility of this .308 platform more than make up for the minor inconvenience of checking for compatibility, so don’t let it intimidate you.

    In fact, because many manufacturers use proprietary designs for their rifles, you’re actually better off building one for yourself so that you’re not locked in to one brand of parts when you want to upgrade and personalize.

    Seriously, have you ever bought a rifle without replacing at least one component to make it even better? If you’re the kind of sportsman that just buys guns to let them sit in a closet somewhere, you should probably go through a few boxes of ammo before you start thinking about custom builds.

    Home building is for the kind of marksmen who know what they want and aren’t afraid to do a little work to get it – not for guys that go to the range twice every year and barely empty a magazine.

    The Big Two
    When it comes to .308 platforms, there are two major players: DPMS and Armalite. You can easily identify the difference between the Armalite-style and the DPMS-style lowers by looking at their shapes. Armalite features an angular cut at the buffer tube, while DPMS lowers have a radial cut at the buffer tube, like this:


    Some companies, like Knight’s Armament (KAC) and Lewis Machine & Tool (LMT), use proprietary designs for their uppers and lowers, but since they’re not sold as individual components, we’re not going to focus on them for now. For most .308 builds, you’re going to pick either the DPMS LR-308 or the Armalite AR-10A/AR-10B as a starting point, and go from there to get the custom result you want. That’s the beauty of building your own – unlike most shooters who would just buy whatever looks neat at the local gun shop, you’re going to set out with a specific purpose in mind and achieve firearm greatness.

    High and Low Rails
    Another thing you won’t run into while building an AR-15 – but you WILL have to think about with its big brother – is the rail system. Armalite uppers generally use something called a low rails system (which may also be called “low profile”), while most DPMS style uppers, use the high rails system.
    High-Profile-vs-Low-Profile-Close-up-300x225.jpg High-Profile-vs-Low-Profile.jpg

    The main difference here, as you’ve probably already guessed since you’re not stupid, is literally the height of the rails. You might prefer the low rails system because of the aesthetic or because of the way the sights sit, and you might prefer the high rails system because there are more options available in the marketplace for compatible parts. It’s completely up to you. The main takeaway here is that when you select an upper and start shopping for handguards, make sure you match them up.

    How To Decide
    So which way to go? There are specific advantages on both sides of the fence. Of course, while we’ve got your attention, we’ll shamelessly recommend that you start with our 80% lowers, which will help cut out a lot of the bureaucratic crap you have to do to own a gun, and which were designed with compatibility in mind. While we openly admit that we’re a bit biased about the quality of our own product (it’s kickass), we’ll still point out that you can start with a Genesis receiver blank and get the best of both worlds for your next build without being locked into either DPMS or Armalite components exclusively. You can read more about our compatibility here.

    Fans of Armalite often cite the superior quality of the barrels that are designed for this system…though we’re going to unabashedly plug ourselves again and point out that you can use DPMS and Armalite barrels with Genesis uppers. In general, though, the overall point is true: for the most part, barrels designed to be used with Armalite’s uppers do tend to be higher quality than those manufactured for the DPMS design.

    Another point of discussion that you’ll often hear among circles of devoted Armalite fans is the fact that Armalite is the original, the very reason ARs are called ARs, and there’s a lot of pride involved in owning the genuine artifact. If that’s important to you, get yourself some Armalite parts.Meanwhile, in the world of DPMS, there’s a good chance you’ve heard that their parts are cheap, inferior, and not worth buying. You might be able to make a compelling argument on that basis in the world of AR-15s, but for .308s, it’s simply not the case. The list of .308 parts available from DPMS, and the myriad of other manufacturers that make compatible components, is actually quite impressive.

    This particular platform is more popular than the Armalite system right now, largely due to the flexibility, wide availability of parts, and the fact that you aren’t locked into using Armalite’s proprietary metal magazines. Magpul even makes a polymer mag for LR-308 rifles made from the DPMS design.With either platform, you can build a great carbine or rifle. The decision hinges on whether you’re looking to build a straightforward, traditional AR-10 (in which case you would be in camp Armalite), whether you need a bit more flexibility to accomplish your goal, or perhaps if cost consciousness is a major concern (which are the major benefits of team DPMS.) Serious shooters like you know what they want, so it’s not a hard decision once you know the facts.

    - Kitty Lusby

    Last edited: Oct 18, 2015
  2. Eli

    Eli Well-Known

    Dec 28, 2008
    Ghettohood - SW Houston

    No, it isn't. The current crop of 'AR-10' rifles is actually based on the smaller AR-15, and share minimal parts commonality with genuine (vintage) AR-10 rifles.

  3. A.Texas.Yankee

    A.Texas.Yankee TGT Addict

    Mar 21, 2012
    I don't think he meant to imply they're exactly the same, merely that the AR-10 came first and share the same concept in design, rather than the 5.56 version being the original. Today's current "AR-10" is based of a version released in the early 90's I believe.
  4. Genesis CNC

    Genesis CNC New Member

    Sep 3, 2013
    I'm fairly confident that is exactly how the writer meant it.
  5. A.Texas.Yankee

    A.Texas.Yankee TGT Addict

    Mar 21, 2012

    Wish I had all that knowledge when I first built my .308. Lots of trial and error. Good news is today is a lot different on the AR 308 market than even 5 years ago.
  6. TX69

    TX69 TGT Addict

    Dec 23, 2012
    I just buy an ARmalite AR-10 complete rifle and start from there.
  7. Shotgun Jeremy

    Shotgun Jeremy TGT Addict

    Jul 8, 2012
    Copperas Cove
    I'm wanting to build an AR 10. I checked out your lowers and am interested...but I'm also looking forward to your future articles as well. Thanks for doing this!

    Sent from my SM-T230NU using Tapatalk
  8. Younggun

    Younggun Ginger Avenger TGT Supporter Admin

    Jul 31, 2011
    hill co.
    The info is good, but it reads to much like an infomercial making the most trivial task seem insurmountable unless you buy product X. I find it to be a turn off when it comes to where I buy and I get the impression it is geared towards new shooters who don't really know what their options are.

    Not bashing you or your business, just giving the point of view of what could be a future customer, but probably not given current advertising practices.


    Sent from my HAL 9000
  9. SC-Texas

    SC-Texas Moderator Lifetime Member Forum Sponsor

    Feb 7, 2009
    Houston, TX
  10. Genesis CNC

    Genesis CNC New Member

    Sep 3, 2013
    Understandable, the writer is of course trying to be helpful to the shooters who don't have this knowledge and she is of course trying to steer that user towards us as that would make her a good writer and keep her employed :)

    The job of any writer is to steer someone toward something, be it an idea, conclusion or a product. Hopefully she also answered the questions that might come up for those that have no experience with such a build.

    There are many options when building you own .308 rifle, we do think our compatibility with parts is a key feature that others do not have, but we are certainly not the only company to go to for such a build... just the best :)

    Take a look at some of the other articles in our blog, some of course are more infomercial than others, but I think you will see we are much more than that.

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