A Four-And-A-Half-Pound AR-15

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How light can an AR-15 made entirely with off-the-shelf components be? Guns & Tactics sought to answer that question with their ultralight black rifle build project detailed in a recent article:

Two years ago, it would not have been possible to build a functioning AR-15 that weighed under 5-pounds with off-the-shelf parts. They were just not available. Thanks to companies like Battle Arms,V7 Weapon Systems and 2A Arms, that has all changed in the last few months.

We set out on a mission to build the lightest AR possible and when it was all said and done, it weighed in right at 4.5 pounds. In this article we’ll share how we accomplished the build and discuss how well it shoots.

There are essentially two metal options when it comes to lightweight receiver sets on the market with more and more coming every day. Take note we said metal, as we are not factoring in composite polymer based lowers.

  1. Battle Arms Development – The BAD556-LW is not only badass looking, it is light: weighing in at 6.84 ounces for the lower and 6.31 ounces for the upper for a combined weight of 13.15 ounces. The BAD556-LW is made from tough 7075-T6 Aircraft Aluminum and precision CNC’d to very tight tolerances. MSRP is $499.
  2. 2A Arms – The Balios Lite is equally as sexy and is mildly lighter than the BAD556-LW. The Balios Lite comes in at 6.5 ounces for the lower and 5.85 ounces for the upper, totaling 12.35 ounces. The Balios Lite is also made from 7075 and retails for $519.99

Either of these options makes a great foundation for your ultra-light build and it really comes down to which looks best to you. We will say that in our experience, Battle Arms puts a lot of attention to detail in their machining and their customer service is top-notch. We have heard great things about2A Arms but we have no experience working first-hand with them.

The article details all the components used in the build, so that the reader can replicate the ultralight rifle if they so desire. Also noted is the rifle’s relatively light recoil impulse. This is because the operating group mass has been reduced, so the “thump” normally associated with the heavy and fast-moving AR-15 bolt group is mitigated. However, its this mass in the moving parts group that lends the rifle much of its reliability, so using lightweight bolt carrier groups may compromise the rifle’s performance in adverse conditions – however, achieving optimum functioning was never the point of the build.

As lightweight components from selector switches to dust covers are released in ever-increasing numbers and variety, it will be possible to build rifles from off-the-shelf components that inch closer and closer to the 4 pound (unloaded) mark.



Nathaniel F

Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. In addition to contributing to The Firearm Blog, he runs 196,800 Revolutions Per Minute, a blog devoted to modern small arms design and theory. He can be reached via email at nathaniel.f@staff.thefirearmblog.com.


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  • MPWS

    For toyees (aka tactical shooters)…. why not. For military application – forget it.

    • Duray

      When did the military start using AR-15’s?

      • Spencerhut

        Are you that dumb or just being a smartass? It’s a couple of drop in parts one way or the other to go from semi/full/burst.

        • Kivaari

          “Drop in parts”?

      • MR

        Early sixties. The early Colt/Armalite full auto AR15s. Then they updated to XM16E1s, then M16s, M16A1s, etc. They don’t use them much anymore, though there’s that HydraMatic M16A1/2 in the other post, so there might be some old warriors kicking around in the back of an arms room somewhere.

    • ValleyForge77

      Agree. Think that sums it up well. Definitely a niche gun with limited (optimized) applications

  • Anonymoose

    Should have dumped the red dot and just used irons (or plastics, I guess- that looks like a KAC Micro rear on there, I think)

    • The sights are Bobro. The articles goes over each part.

      Also an optic, light, and sling (w/mounts) aren’t included in the 4.5lb weight. But heck as long as you don’t go nuts you can probably mount all that and still weigh less than an out of the box Colt 6920.

    • MR

      Full load of tracers, FTW!

  • TheNotoriousIUD

    Awesome, now I can carry even more ninja stars.

  • Ethan

    Light on the shoulder, heavy on the wallet.

  • Jack

    They wanted light but they used the longest hand guard they could get? The kmrs are light but they could have saved some more there.

    A buddy pieced together a rifle with mag tactical upper/lower, ap hand hard, light profile barrel with adjustable gas block, lightweight bcg, standard buffer setup with an mft minimalist stock. It cost him under $1k and came in at 4#13oz. He did it about a year ago. This doesn’t seem like that big an accomplishment.

    • Anonymoose

      Should have gone with a carbine-length carbon free-float tube, or even better- just put a magwell grip on and omit the handguard all together. :^)

      • MR

        Just upgrade to thicker heat proof gloves.

        • CruisingTroll

          Thicker, HEAVIER, heat proof gloves. The improvement in tactile feedback will so be worth it.

          • MR

            “…achieving optimum functioning was never the point of the build.”

          • MR

            And if an optic, sling, and light aren’t included in the final weight, I’m going to ASSume that the gloves won’t be either.

          • CruisingTroll

            If you’ve ever burned yourself on a hot barrel, you might conclude, as I have, that a burn hazard such as this puts the weapon into the “non-functioning save for an emergency” category.

            Still, I do see the value of builds like this, because it’s by pushing the boundaries that things can improve. The next iteration (whether by these folks or someone else) is going to be along the lines of “okay, we’ve made it this light, now let’s see how we can get to optimum functioning.” Then they’ll have a 4lb AR that functions flawlessly, but costs $25k, so the goal will be to get the cost down, after which the goal will be lower weight again…

            Rinse, lather, repeat.

      • sam

        Indeed, delete the handguard like the ones in Escape From New York. Techno-western look, weight savings, fewer parts, increased burn hazard: total apples-to-apples superiority over an AR with handguard.

    • It honestly isn’t anymore.

      In the past building a super light weight AR meant personally taking the parts into your shop and milling excess weight off each part. Hoping that you are correct in that the material is unneeded.

      Now you can order it all off the internet and assemble it.

    • raz-0

      It’s not. I built a 5lb 2.8oz rifle out of my leftovers box and the purchase of a light contour barrel and a midlength ap custom tube. Granted, “iron” sights, but it works.

    • Cymond

      The KMR is super light but they could have used a shorter length. I’ve considered carbon fiber handguards, but you have to run optics of you don’t have a railed handguard. Optics are great, but if we’re competing on weight, the the MFT folding polymer sights are supposedly 1/2 ounce each. If true, then the extra ounce of a KMR10 is a better trade off than the 5 ounces of a red dot.

  • Spencerhut

    All the real weight is in the bolt carrier and the barrel. Light is nice, but we’ve snapped one of these super light AR’s right in half at the buffer tube threads by dropping it flat from ~3′ off a concrete floor. One drop. Let me tell you we were all a bit surprised how easy it broke.
    No “I’m up. He sees me. I’m down.” drills with the light ones.

    • Will P.

      Not everyone that owns an AR wants to be a tacticool operator. Some of us out there just like ARs, and don’t pummel our guns for fun.

      • Jack

        You mean I can stop growing my beard and just “have fun” with my hobby? Thank God.

        • Will P.

          I didn’t say that! If at least half of your paycheck and a second mortgage isn’t going into tactical gear you’re not Merican! Lol

        • Non-Operator

          HAHAHAHA!

        • Grindstone50k

          But I like my beard

      • The super light weight movement is borne out of people that wish to lighten the carry weight. Though they may not purposely abuse them, they will take more abuse than a range toy, in that at the very least they will be carried around a property or such.

        So I believe that durability is a concern, even if they using it as a tool to beat up the ground.

    • Squirreltakular

      Was the receiver polymer? Otherwise, I don’t see how the weight of the overall rifle would make a difference if the receiver and receiver extension were the same…

  • ValleyForge77

    That is definitely cool. If I was going to do another AR build, I’d seriously consider something similar, as I’ve been on a ‘light-weight’ binge ever since I built my first AR – and there is so much cool lightweight stuff out now, where there wasn’t 10 years ago. Definitely a niche gun though, as he says: not build for reliability/durability in adverse conditions…

    I was of course questioning that if they really wanted to go as light as possible, why then slap a heavy-assed Trijicon SRS on top, when an Aimpoint Micro on a Larue LT751 comes in at a scant 5.4 oz (vs a whopping 13.8 OZ for the SRS). But I see that PPGMD already answered that below…

    Anyway, I found that to be pretty cool and informative. Thanks!

  • Joshua

    And he chose to use a 18oz optic…

  • Vitsaus

    Another thing that greatly reduces the weight of rifles: exercise.

  • RickH

    I don’t care how light my AR is, just as long as it’s………………sexy………….

  • RocketScientist

    Came here to post this, you beat me to the punch. Pretty impressive build. Of course durability is compromised using a polymer lower and FCG, but I think for anyone not taking it into a warzone thats just fine. I went out onto our lab floor just now and found some hardware that weighs right at 59 ounces. Hefting that, and imagining that’s a fully functional AR is pretty impressive.

    • SubSixtyAR

      Hey guys thanks for posting about me!

      Been very busy with work recently so haven’t had much time for my hobbies. Will hopefully be posting this week about the gas block I chose (SLR Rifleworks, nothing else comes close) and then doing a final run down of the complete rifle.

      Keep checking back!

    • Kivaari

      I’ve fallen so many times in the brush, I wouldn’t go this route. I bent a Colt CAR15 after a misstep.

  • tony

    Too rich/light for my blood

  • Steve Truffer

    Just a quick look (AK guy, AR’s aren’t my expertise), wouldn’t Smoke Composite’s stock and handguard be a wiser combo? Both are lighter by a fair amount – the stock is almost half the weight, and the handguard better than 25% lighter, giving ~6 oz in total savings (though bumping cost by $80)

  • mig1nc

    Would look nice with my 17oz suppressor on it.

  • Kivaari

    Function – reliable functioning and the ability to take a beating is worth the extra weight.

    • Dan

      They are not building these to be used for combat in afghanistan.

      • Kivaari

        I know. I buy and use guns that are fit for use in harsh environments. Even though I no longer get close to where it may be needed, I like rugged firearms.

  • Cymond

    My lightweight build currently exists only on paper, but specs in at 55 ounces, which is less than 3.5 pounds. However, that build sacrifices almost everything for weight, including using a polymer receiver that the company explicitly says is only meant for demonstration, competition, etc because it is not durable. However, a Mag Tactical magnesium alloy lower would only add 2.3 ounces.

    My build is based on subsixtyounces.tumblr.com with some changes.

    • Dan

      While building my ultralight AR, I’ve found that many “lightweight” parts have incorrect quoted weights and turn out to be heavier than claimed.

  • CS

    A polymer lower receiver would have saved a lot of weight too.

  • LevelHeaded