Last year, I started Project Icarus: to design a very accurate, ultralight AR15 using off the shelf parts.  My goal was a sub-6lb rifle, with the suppressor and optic included in that weight and I wanted to keep the parts as durable as possible, so I shied away from the use of plastic receivers.  Since off the shelf parts are designed to be strong and light already, I didn’t do any drilling, skeletonizing or anything to further reduce the weight.

At the end of version 1.0’s build, I had an AR15 that weighed in at a svelte 5.776, with suppressor and optic included.  While I had achieved my goal, I felt there was still too much weight up front that I could cut.  There was steel where titanium could replace it, there was aluminum where 2055 Li-Al alloy could be.  Taking the rifle back to the butchers block, I made the following changes.  As I’ve covered many of these parts in my previous build articles on the upper and the lower, the most detail will be dedicated to new parts.



This is where the most has changed.  The excellent Odin Works barrel was very accurate, but nearly a half pound away from being “ultralight”.  Their O2 Lite rail was nearly anti-gravity, but I found another rail that was not only longer, but also lighter and stronger.  Changing from a (stainless steel) adjustable gas block to a (titanium) fixed block meant I couldn’t use Rubber City Armory’s titanium BCG.  I needed an adjustable BCG, and it needed to be lighter (!) than RCA’s.  Here’s what stayed the same.


What’s new in the Version 2.0 upper?

Faxon Firearms 14.5″ 5.56mm pencil barrel                                     18.4 oz            $169

Ultralight AR15 version 2.0 | 2 pound upper (part 1)
Faxon 14.5″ pencil barrel

V7 Weapon Systems titanium gas block (with gas tube)                 1.4 oz             $70

Ultralight AR15 version 2.0 | 2 pound upper (part 1)
V7 titanium gas block

V7 hyperlight magnesium 11.1″ forend (w/hardware)                    5.57oz          $279

Ultralight AR15 version 2.0 | 2 pound upper (part 1)
V7 hyperlight forend

2A Armament titanium regulated bolt carrier (RBC)                     6 oz              $439

Ultralight AR15 version 2.0 | 2 pound upper (part 1)
2A Armmament RBC

There’s some awesome stuff here, so lets dig in.  As I mentioned, the Odin Works barrel was very accurate but I shaved about 7.3 oz off by changing into the Faxon pencil profile barrel which is the industry leader for ultralight builds.  It has a reputation for being a solid performer despite its scant weight, so I’m excited to really stress it out.

The forend is the V Seven Weapon Systems Hyperlight 11.1″ magnesium keymod version.  Coated in a plasma deposition process, given 3 integral QD sling mounting points and bolted to a 7068 super-aluminum barrel nut, this is a thoroughly engineered front end.  At 5.57 ounces (with barrel nut and mounting screws), this cut more than an ounce-and-a-half from the 9.5″ rail that preceded it; longer versions are available and shorter versions are coming I’m told.

Moving from the adjustable stainless gas block to the V7 titanium block shedded a full ounce.  This is designed to be a very tight fit, expect to use a bit of oil to get it on.  As with every V7 product I’ve tested, fit and finish are flawless.

As I dropped the (necessary) adjustable gas feature from the gas block, I needed to add it back in elsewhere.  Enter the fantastically light 2A Armament RBC.  This uses a T6 torx to adjtool ust a gas gate in between the bolt carrier and the gas key.  Adjustable from fully open to fully closed so it can be tuned for nearly any buffer weight/ammo combination.  The torx head screw is accessible through the ejection port door, so there’s no need to break down your rifle to adjust it.  The RBC has a steel bolt, titanium bolt carrier main body and an aluminum 7075-T6 rear body portion: this is incredibly high-tech compared to your standard BCG, only 6 oz complete and is adjustable so you can dial down the gas, preventing the bolt carrier group from hitting insane velocities.

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Ultralight AR15 version 2.0 | 2 pound upper (part 1)

After assembling the upper, I put it on the scale (without optic or suppressor, yet) and it came in at an incredible 2 lbs, 9.6 oz or 2.597 lbs.  All told, the upper alone cost $1440.90, at a rate or $34.65/ounce.  An expensive upper to be sure!  Ultralight builds are definitely pay-to-play.  Next article I’ll cover the lower receiver in detail, then it’s off to the range to see how it all performs!

Stay tuned…

Rex Nanorum