The Light Rifle AR-15 Build – Make It Long

Light Rifle AR-15 Build Feature Image.
June 11, 2020  
Categories: Guns

The Light Rifle isn’t named because it’s necessarily a lightweight rifle. It’s honestly a little heavy compared to a standard AR-15 with a 16-inch barrel. Light Rifle is a specific term I use to describe it because it fires an intermediate rifle round that’s light compared to something like a 308 Winchester round. The term rifle is also a bit vague, but in this build, I specifically mean a full-sized rifle, not a carbine.

The Light Rifle AR-15 build is, therefore, an intermediate caliber, semi-automatic, full-sized rifle. Light Rifle can also refer to the fact that this Rifle is light on the wallet, as none of the parts are incredibly expensive. However, none of them are pieces of junk either. My ultimate goal was to make a rifle that can do a little bit of everything and also operate within a range of 5 to 500 yards. Here’s how I built this full-sized rifle with parts from Aero Precision, Magpul, Athlon, and Streamlight.

Why A Rifle

In the age of the carbine, why would I want a big, bulky, long and heavy rifle? It won’t even fit in my standard AR 15 case. Well, as an official old man, I never found my M16A4 bad at anything. Sure it was bigger than an M4, but in reality, you can clear rooms and operate in and out of vehicles with a full-sized rifle. Sure it’s not as comfortable as it could be, but I never felt handicapped by it. I’m also a gorilla, so maybe that’s why I’m so comfortable will a full-sized rifle.

A full-sized rifle with a 20-inch barrel is a much smoother shooter than a standard carbine. That rifle length gas system is incredibly comfortable and very soft compared to a carbine or shorter gas system. Recoil, concussion, and muzzle rise are light and very smooth. Over-gassing isn’t an issue with a full-sized rifle, either. This makes the Light Rifle much more comfortable to shoot and handle.

Also, the 223 Remington and later 5.56 NATO rounds are designed for 20-inch barrels. A 20-inch barrel maximizes the velocity of the round and increases its effective range, and it’s penetrating power. This makes the Light Rifle a very capable rifle at various ranges. Another benefit to the 20-inch barrel is that most 223 Remington hunting ammunition is designed to expand at the velocities a 20-inch barrel provides.

The Base of the Light Rifle

The Light Rifle started life as an Aero Precision M16A4 clone. It’s a perfect base rifle for this build. I chose an Aero Precision M16A4 because it is extremely well made, accurate as a laser, and fun to shoot. Best of all, it’s an affordable option should you desire a full-sized rifle. Aero Precision makes some awesome rifles, and I think a lot of people sleep on Aero.

Magpul Threw Up All Over My Gun

Yeah, I know what you’re thinking, what is it, 2012 again? Admittedly furniture for rifles with FSBs and 20-inch barrels is rare. So are fixed stocks. The Magpul handguard and stock are old, but still reliable, and both are excellent options.

The Magpul handguard offers a modern M-LOK mounting option for accessories and is relatively affordable compared to a Knight’s rail. These were two important features for me. It’s also comfortable to grip, and I do appreciate the aesthetically pleasing design. It’s also relatively lightweight and does a great job of keeping the heat off your hands.

Light Rifle AR-15 build with magpul handguard.

The Light Rifle stock is a simple design, but it’s much better than the standard A2 length stock. It’s shorter and is the same length as an A1 stock, and this makes it about as long as an M4 style collapsed stock fully extended. It offers a very stable platform to mount yourself too and provides you a very beard friendly stock. I’m a big fan of fixed AR stocks, and I chose the Magpul MOE model is the most modern and ergonomic option.

Light Rifle AR-15 Build Magpul MOE stock

The Magpul MOE stock also offers plenty of sling mounting options, and a large compartment to store tools, a cleaning kit, or even Reese’s Pieces. A fixed stock also ensures that every time you mount the weapon, it’s exactly the same.

Optics of the Light Rifle

This is simply a rifle, not a DMR, or a Sniper rifle. It’s just a rifle with an effective range of about 500 yards. With that in mind for me to own 500 yards, I need an optic with magnification. I went with the Athlon Argos BTR Gen 2 1-8X. This is the perfect optic for this type of Rifle. It allows me to engage with ease at any range from 5 to 500 yards.

Light Rifle - Athlon Argos BTR Gen-2 1-8X optic.

The Athlon Argos BTR is bright, clear, and can be used at any range between 5 and 500 yards.

It’s very clear, provides an excellent reticle for various engagement ranges and even provides holdovers for wind calls and bullet drop. At close range, the second drop reticle works to compensate for height over bore and allows me to be plenty precise within 15 yards. This Athlon optic fits my goal of having a rifle that can be used at any range between 5 and 500 yards.

The Athlon Argos BTR is bright and clear and still remains somewhat lightweight. The price is relatively low as well, at least when it comes to high-quality optics. The Athlon Argos BTR GEN 2 and LPVOs, in general, are an awesome option for any rifle.

Lighting Up the Light Rifle

Of course, as you can see, I’ve also attached a light to my gun. Again I took a simple but affordable route from Streamlight, which is a proven company. I went with a simple Streamlight ProTac. This 625 lumen light is about the best hundred bucks you can spend on a weapon light. It comes with a tail cap, as well as a pressure switch, and the integral mount is easy to use.

Light Rifle - Streamlight ProTac

The Streamlight ProTac offers 625 lumens.

Streamlight makes tough lights, and they are also an affordable option. For the price and quality, I don’t think there is a better option. The Light Rifle AR-15 is properly lit with a Streamlight ProTac, and I feel it’s an optic well suited to the task at hand.

The Light Rifle Build

This was a bit of a passion project. While I recognize it’s not going to be the first choice of the soldier or police officer, I do see it as being a handy rifle. It can be an effective hunting rifle, and it can be a defensive rifle, a target rifle, or even a bush rifle. The Light Rifle AR-15 build is also an affordable option made from quality parts. It’s not for everyone, but I think it has its own charm. back Breach-Bang-Clear

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Travis Pike

Travis Pike

About the Author


  1. CavScout62

    I’ve never stopped running a 20” and won’t as chopping the barrel defeated the purpose of going to the Poodle Shooter altogether weather we are talking range or terminal performance.

  2. Dave Hernandez

    The switch to 62 gr bullets occurred with the 20″ barrels. I have run 20″ barrels with 1:12 twist, 1:10 twist, 1:9 twist, and 1:7 twist. The original 55 gr set-up was a 20″ with 1:12. After the 62 gr bullet was introduced, the standard barrel was a 20″ with 1:7, but then they backed the twist rate of to 1:9.

    Then when shorter barrels started being introduced, the velocities dropped significantly, to the point that the 62 gr bullets were marginally effective and really only at close range. The main reason the shorter barrels were widely adopted was because the longer barrels caused egress problems when exiting vehicles, especially HMMWVs.

    Eventually the Mk 262 77 gr was introduced to try to make up for the shortcomings of the short barreled rifles.

    The short barrel craze has caused a lot of people really compromise the ability of of the platform to perform. I personally dislike running less than an 18″ barrel. When I put people behind an 18″ or 20″ barreled AR-15 and show them what the rifle can really do, a lot of them start rethinking the whole short barrel fad.

  3. Lonnie G Hopson

    I must have missed the sentence about the differences in twist rate between older 20″ barreled rifles and the 16″ barreled carbines. The older, longer rifles were set up to shoot 55 grain and the shorter 16″ carbines were/are set up to shoot 62 grain penetrator rounds. These differences in the rifling’s and lengths also affect the felt recoil.

    • Lonnie G Hopson

      I forgot to mention the original twist rates in the older rifles were 1 in 12, which made for inaccuracies. Then is was sped up some to 1 in 10, I believe. Then with heavier rounds and shorter barrels 1 in 9 for 55 grain and 1 in 7 for 62 grain.


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