The AR was designed to be a lightweight rifle. So why does mine weigh as much as an M1 Garand? I set out to try and build the lightest AR I could while both avoiding the use of polymer or carbon fiber and maintaining all of the rifle’s functionality. I also opted to keep the maximum versatility in terms of mounting accessories and optics.

I weighed each part looking for the lightest and highest-quality components from dozens of manufacturers. The upper and lower receivers are made by MAG Tactical Systems from a proprietary magnesium alloy and weigh 35 percent less than standard aluminum receivers.

I opted for a mid-length gas system for reliability and recoil reduction with a Spike’s Tactical nitride-coated, mid-length gas tube and the VLTOR Low Profile Low Mass Set Screw Gas Block. I used a 14.5-inch, pencil-thin, fluted Bravo Company Manufacturing lightweight cold-hammer-forged barrel with M4 feed ramps and a 1-in-7-inch twist rate. I used the new BCM KMR 10-inch, free-floated handguard, which is made from a magnesium alloy that’s extremely lightweight. The KeyMod Rail System allows for multiple accessory attachment points as well.

The new Mission First Tactical Battlelink Minimalist Stock I selected was ideal. It is the lightest six-position tactical stock you can get. I weighed several pistol grips as well and found that the absolute lightest is the Magpul MOE-K Grip.

Internally, I used the Rubber City Armory Low Mass Competition Bolt Carrier Group, which is heavily skeletonized and shaves almost 25 percent off the weight of a standard bolt carrier group. It is also black nitride coated for superior corrosion and wear resistance. Finally, I installed a GI lower parts kit from DPMS and several small parts from V7 Weapon Systems, which makes 7075-T6 aluminum parts for the AR to replace steel parts.

On the range, I installed the fully adjustable Spike’s Tactical Billet Micro Front and Rear Sights, which are the lightest metal backup sights you can get, and the Bushnell TRS-25 HiRise red-dot sight, which features a 3-MOA dot and 11 brightness settings. The rifle performed exceptionally well with zero malfunctions, thanks to the gunsmiths at Sterling Arsenal, who completed the build.

The rifle alone, without sights or magazine, weighed 4.75 pounds. It is certainly possible to go lighter, but not by much without sacrificing some functionality or using extensive polymer or carbon fiber.

To read the full details, check out the 2015 issue of BLACK GUNS, available July 22, 2014. To subscribe, go to /black-guns-buyers-guide.