Sunday, July 4, 2021

What Would Stoner Do? - A Custom AR15 Prototype

 What Would Stoner Do? - A Custom AR15 Prototype

What if Eugene Stoner had somehow seen or imagined all the cool AR design innovations and manufacturing techniques of today and decided to build a custom AR for himself with the tech from the 1960s? It is a question that comes to mind after a few scotches. Here we are today making all these tricked out ARs, but WWSD - What Would Stoner Do?

A few years ago, I worked with Brownells to build the starting point of this build - something that never was. See that build here. As you might remember, Stoner built the infamous hyperlight prototype based on the AR10 platform, but never an AR15 prototype. A few years ago, I built a representation of that companion prototype of the AR15 platform - that build was used as a starting point for this custom Stoner build. My previous 6-lbs, 1-ounce prototype build really answered the question of what would that smaller Stoner A15 prototype potentially have looked like if he would have used a touch of the modern designs that could have been manufactured back then. Where I stopped injecting new design elements with that build was about where Stoner left off with the AR10 platform, plus a few tweaks like adding a skeleton Ace stock, HiperFire EDT trigger, and Fiber Optic front sight post. Those few gentle upgrades were based on the supposition that he rethought a few things in between his original AR10 prototype and release of the AR15 while still remaining well within materials and manufacturing reach back then.

If Stoner would have seen or imagined all the tricked out AR formats now, he would have certainly built one himself. For this build, I wanted to build the custom AR15 that Stoner would have built for himself based on current design innovations that could have been manufactured then and some elements that might have required some custom hand work. It is easy to speculate his intent for a custom build since much of Stoner’s design work was focused on reducing weight and increasing portability. He also had access to the most cutting edge materials, manufacturing and talent in the aerospace and firearms industry. 

Stone was big on light portable rifles and in fact his first produced rifle was a take-down bolt action AR-5 survival rifle chambered in .22 Hornet. The AR-5’s barrel unscrewed similar to the AR-7 .22LR Henry Survival Rifle (another Stoner design) currently produced today for easy storage even in small spaces. The focus on the AR-5, AR-7, and most other designs including the AR-10 prototype were all around lightweight newer materials and manufacturing methods while retaining functionality. Stoner also agonized over ergonomics, comfort and shootability. Stoner was somewhat limited in that the final intent of his designs were to make money and obviously no one in their right mind would shell out $2000 for a custom rifle - right? What if he didn’t have this limitation at that time and was building for fun. For this build, I pimped out my original Brownells based AR15 prototype Stoner style with weight, stowability, ergonomics, comfort and shootability as design goals.

The Original AR15 Prototype Build

My original Brownells 6 lb, 1 oz AR15 prototype build started with a faithfully recreated XM16E style A1 upper (aka carry handle upper) and matching Brownells branded M16A1 style lower receiver that Brownells worked with Nodak Spud to faithfully recreate. For this build I retained the carry handle upper, 18” Faxon 5.56 Nato pencil barrel, Daniel Defense front sight base, Clark carbon fiber handguard, but from there a number of upgrades were made. The idea for this build was to really push the limits based on innovations and designs of today without exceeding the machining, forming capabilities and materials of 1956-1960s. We have a whole bunch of cool AR15 design tech that could have been made back then and I wanted to base this build on that idea.  When I look at custom hand formed and tooled firearms from the 1800s and early 1900s, it should be obvious that anything is possible, it is just the speed of manufacturing, cost, and the materials that limits the possibilities - don’t believe me disassemble a Browning A-5 Shotgun.


Receiver & Ergonomics - Forging was typical technology of the day which means that the receiver did not have to specifically look like Stoner originally designed it and could have included many more custom elements. A modern example used in this build was the San Tan Tactical SST-15 ambi lower; though it is a 5-axis billet machined design it could have been almost completely formed by forging and required minimal finish machining.

In fact the similar innovative design and ambi functionality offered in the lightweight MOD2 lower receiver from Primary Weapons Systems is a forged lower receiver just like Stoner could have manufactured. Frankly, I would have used a PWS MOD2 lower here as a perfect example of what forging can deliver, but could not get my hands on one.

PWS Mod2 Forged Lower Ambi Reciever

The San Tan SST-15 and PWS Mod 2 lower receiver design innovations would have added a lot of ergonomic improvements, shootability, and features including ambi-controls for magazine and bolt release. Both the PWS and San Tan lowers also feature integral adjustable tension screws to tighten upper and lower receiver fit, and ambi controls for magazine and bolt release. I added a Battle Arms Development ambi-selector to assure that this AR15 of yesterday is just as comfortable for lefties as correctly handed people. :)  Battle Arms Development take-down pins were used as well to improve the ergonomics of pulling pins and disassembly. For the grip, I used a mil spec standard finger groove grip, ground it down flat, hand stippled it with a wood burning iron, and then milled slots for a custom paracord wrap. The last final ergonomics touch is a latchless Mega Arms ambi-charging handle on the upper. I think Stoner would have liked these extra details. 

Carry Handle Upper & Improved Sights - The XM16E style A1 (carry handle) upper, WMD NiB-X Bolt Carrier Group, 18” Faxon 5.56 Nato pencil barrel, forged Daniel Defense front sight base, Clark carbon fiber handguard were carried over from the previous build because they worked amazingly well. The upper was still a great base to create a custom build from.

Stoner would have also likely carried over the A1 style carry handle upper as he believed it offered a lot of utility carrying the rifle, but he would have wanted to improve the sights for night use. He would have looked at something to illuminate the front post beyond fiber optics and would have found a way to use Tritium (discovered in the 1930s) on the front sight post. XS Sights’ CSAT Precision Target sight set delivers both a daytime high contrast white stripe front sight with tritium insert and a rear triple aperture designed by Paul Howe that combines a standard ghost ring 100-yard aperture with a dual aperatured second sight with 100-yard precision peep aperture and a 7-yard zero top notch aperture. Though a standard ghost ring aperture is just a flip away, the single high precision and notch aperture allows shots from 7-yards to 100-yards plus without flipping the sight. This is definitely an innovation Stoner would have loved because it adds zero weight, improved sighting ergonomics, and improves day/night sighting options.  

Low Mass and Adjustable Gas - The WMD bolt was retained, but the carrier was replaced with a JP Rifles Lo-Mas LMOS Aluminum Alloy carrier to reduce weight along with a matching low-mass buffer. Up front, the Daniel Defense front sight base was drilled and tapped as a converted adjustable gas block to take advantage of the lower mass carrier and buffer assembly. Many… many years ago this was how myself and others created the first adjustable gas blocks before they were widely produced. To pull even more recoil out of the Stoner custom prototype and limit muzzle rise, a PWS FSC brake was installed. The brake combined with the low mass carrier & buffer and adjustable gas block delivers a sizable overall weight reduction and a near recoil-less gun with negligible muzzle rise. Stoner would have thought these updates were addressing a whole boatload of things on his wish list including increased shooter comfort, faster follow up shots, improved shot-to-shot accuracy and an overall lighter gun.

Weight Reduction - To reduce the overall weight even further beyond the carrier/buffer, the astoundingly light 4.3 ounce Brigand Arms Carbon fiber stock would have been possible with carbon fiber and even fiberglass forming of the day. Though not as rugged as the previously used Ace Skeleton stock on my original build, it would have certainly been as strong and Stoner’s choice to conserve weight on a personal custom build. Another innovative PWS part I use is their PWS Ratchet Lock Castle Nut & Endplate set which prevents any loosening of the buttstock without requiring castle nut staking.

Portability & Stow-ability - Portability and take-down features were really appealing to Stoner as were showcased in the AR5 and AR7 designs, so I thought it appropriate to add a Gen1 Dolos Take Down adapter to this build. The Gen 1 Dolos kit is no longer made in favor of the new Gen 2 kit, but the Dolos kits do happen to be compatible with Midwest Industries handguard threading and perfectly sized to epoxy on a Clark Carbon Fiber Handguard.

The original carbon fiber handguard was trimmed down to fit behind the front sight base to allow room needed for barrel removal. The Dolos system addition allows the entire 18” barreled rifle to be tucked into nearly any backpack and assembled/disassembled in just seconds. It is faster than unpinning the upper and the net stowed length is just the barrel length instead of the barrel length plus attached receiver length. This would have been a fairly simple to manufacture design innovation he surely would have wanted to use this to check off his portability and stowability goals. [Pictured - The Customer Prototype build slips easily into a Hazard 4 Plan B sling pack. ]

Trigger Tech - I used what is arguably the most advanced trigger on the market, the HiperFire HiperTouch Competition trigger. These would have been possible with forgings and some manual milling and delivered a fast and advanced trigger, this would have been the ultimate for Stoner. 

Adaptability & Training - The last and final accessory would surely have been a CMMG .22LR adapter kit. Stoner loved small caliber arms and touted continual practice. What better accessory would there have been than a CMMG .22LR kit that would have allowed inexpensive practice and even quieter small game hunting? He would have considered this essential.


This build weighs in at a feathery 5.3-lbs which is nearly a 1-lb weight reduction from my original prototype build. Considering this is an 18” barrel that is quite an accomplishment. More importantly it would have hit the X on Stoner’s primary weight reduction design focus. With a scant 5.3-lb AR that can also be easily disassembled into a pack, it would have been a go-to favorite gun for him on every trip all while still delivering far beyond the ergonomics, comfort and shootability of the original design. 

With a 5’ish-lb gun he would have experienced the magic that low mass carriers, buffers and adjustable gas blocks can deliver. What should be a gun that lets you feel every pull of the trigger, instead delivers recoil more similar to a pellet gun recoil all while shooting flat and very fast. With the drop-in .22LR CMMG kit this particular Faxon barrel has delivered .5-inch 25-yard groups with SK Rifle Match ammo and is more than adequate for a fun day plinking at the range and using typically does not require me touching the sight zero. 

As I exclaim “holy freaking hell” every time I lift one of my heavy precision ARs, I think of this gun. It delivers an awe-inspiring set of features for a rifle just over 5-lbs. Had I stayed with a standard lower receiver or even a 4.3-ounce polymer James Madison Tactical 80% lower and left off the Dolos kit, retained the lighter HiperFire EDT trigger, the build would have tipped under 5-lbs. This has become one of my go-to fun guns and without question makes me appreciate the design brilliance of Stoner. He would have been impressed with all our advances on the platform today.  For me this represents everything that was, could have been and is today around the flexibility, utility, and configurability of the AR15 design and should be no surprise this is one of my more heavily shot firearms. 

A huge thanks to Brownells for their continued support and support in helping make this build possible. If you have not been to Brownells, they have everything you could need for any AR build. 

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