In part two of my ongoing series detailing an ultralight AR-15 build, I’m covering the upper receiver.  The goal of this rifle is to come in under 6 lbs with for the rifle, suppressor and optic.  Part I in the series dissected the lower, so let’s break down the parts list of the top half.

Sorted by manufacturer:

Bootleg Inc.

Ultralight AR-15 Build Part 2 | The Upper

One of the most oft used uppers for lightweight builds, Bootleg’s slab of 7075 aluminum is light, slick looking and well crafted.  The scalloped and cut sides give a distinctive look as well as cutting all unnecessary weight without sacrificing strength.

Rubber City Armory

Ultralight AR-15 Build Part 2 | The Upper

One of the lightest and best reviewed BCG’s out there and with good reason.  Extremely light and yet yields massive strength by virtue of its nitride treated titanium which increases wear resistance and prevents galling.  The bolt itself is tool steel, yet with the same coating.  A lightened BCG provides lower weight as well as lower reciprocating mass.  While this does necessitate a different balance within the recoil system, it also provides for unbelievable fast and smooth shooting.  Many shooters think this is only the provenance of competition shooters who never deviate ammo.  Those competition shooters respond with their own experience showing astronomical round counts, high reliability and nowhere near the ammunition pickiness we’re led to believe by naysayers.  The standard system is often way overgassed and uses mass to time the system for full-auto fire.

Odin Works

Ultralight AR-15 Build Part 2 | The Upper Ultralight AR-15 Build Part 2 | The Upper Ultralight AR-15 Build Part 2 | The Upper

The O2 Lite is… oh too light!  A strong forend despite its scant weight, the O2 is also available in MLOK flavor.  Inside diameter of 1.6″ in case you’re interested in “the tuck”.  The barrel isn’t the lightest on the market, but it isn’t overly heavy and offers a 1 MOA guarantee.  The tunable gas block adds the necessary function of reducing the gas flow, thus slowing the lightened BCG and preventing it from hulk smashing the inside of the receiver extension.  It uses two screws in one hole, one to adjust the gas flow and the other to prevent the first from moving once tuned.

Radian Weapons

Ultralight AR-15 Build Part 2 | The Upper

Ambidextrous levers provide dual-side charging ability when using the traditional finger-thumb style or when blading.  The ported design helps reduce gas blow back into the shooters face a bit.  When combined with the RTV silicon trick, this is the do-it-all charging handle.

Suppressed Armament Systems

Ultralight AR-15 Build Part 2 | The Upper

Having recently written up the TOMB suppressor mount/muzzle brake and Reaper Ti suppressor, so I’ll go over the high notes.  This can is rated for the .300 magnums yet lighter than many dedicated .223 cans.  The mount doubles as an effective two-chamber muzzle brake in it’s own right.  Titanium wins and SAS is knocking out awesome products.

Vortex Optics

Ultralight AR-15 Build Part 2 | The Upper

A micro red dot sight is just as comfortable on a handgun as it is on a shotgun or rifle. This little guy fits the bill for an ultralight rifle quite well.  The 3 MOA dot isn’t for long-range or precision work, but it sure is fast.  Battery life is between 150 and 30,000 hours depending on setting.

Heading over to my trusty scale, the upper comes in at 3.351 lbs without optic or suppressor.  Add on the Vortex Venom and we’re at 3.48 lbs, screw on the SAS suppressor and we’re at 4.184 lbs for the upper.  Cost for the upper alone (not factoring sales or reduced street prices) is $1388.90, with the $1054 suppressor and $229 optic bringing the total as-built to $2671.90.  This is a per ounce cost of $39.62.  Without the suppressor that drops to $28.99/oz. While there are some polymer parts out there that are lighter, I’ve gotta say I don’t trust em.  I know Glock and the like have been producing polymers that have held up to decades of abuse, but I want to see an AR poly parts manufacturer with a longer track history first.

Ultralight AR-15 Build Part 2 | The Upper

The lower is at 1.592 lbs after swapping out the standard buffer for Taccom’s Carbine Recoil System (which wasn’t available at the time I had finished the lower).  This bring the total weight of the rifle to 5.776 lbs with suppressor and optic!  I’ll be writing back before long with a range report, covering the tuning of the gas system, how the recoil system works and what kind of accuracy I can wring out of this.  After that maybe I’ll head back to the drawing board to see where I can cut some more weight….

Stay tuned!