Issue 38 BUILDSHEET: 7.62×39 AR Steven Kuo 1 Comments, Join the Conversation We Build an AR That Takes AK Mags In this issue of RECOIL, we celebrate the AK, in all its splendor and variations. What better way to honor it than by building a 7.62x39mm AR. And not one that takes weird unreliable mags shaped like the letter J, but one that happily feeds from the original banana mag. Billet Rifle Systems offers a receiver set tailor made for this build. The lower receiver has a yawning AK magwell, a stainless steel cross pin, and a paddle mag release to accept rock-n-lock mags like an AK-inspired AR truly should. The upper sports a sweet non-reciprocating side charging handle, on the left side where proper-handed shooters expect it to be. BRS sells entire rifles too, but we wanted to roll our own AK tribute, so we used their upper, lower, action spring, and custom bolt carrier group as the basis for our build. Unlike CMMG’s 7.62×39 Mutant, with its stretched dimensions, BRS’s receivers conform to the standard AR-15 footprint — thus explaining the slightly cramped trigger guard. Our next selection was Faxon’s nitrided 16-inch barrel with mid-length gas system. BRS recommended opening up the gas port by a few thousandths of an inch for optimal function. We topped the barrel off with a SureFire muzzle brake and suppressor adapter so we could attach a can for our next hog hunt. An under-folding stock wasn’t an option, but we put a side-folding stock on it with LAW Tactical’s clever stock adapter. Mission First Tactical’s buttstock was both functional and evocative of metal folding stocks found on various AK-pattern rifles. You can’t discharge the rifle with the stock folded, but it’s very handy for transport — and, let’s be honest, it looks cool and was perfect for our AK theme. When you picture an AK in your mind, we’d bet that it has wood furniture. It took some digging, but we found hand-finished walnut rail panels and pistol grips from Black Wood USA; their military red finish was perfect for our theme. The M-LOK panels are a little chunky, a great match with Centurion Arms’ very low-profile 15-inch handguard. On top, we attached a Burris XTR II 1-5x scope with CQ mil reticle, a nice match for this rifle. We initially put it in a QD mount but kept hitting the levers when working the side-charging handle; we switched to an Aero Precision mount, completely smooth on the left side and very light and affordable to boot. For backup iron sights, we mounted Sidewinder sights from Strike Industries, which flip out as 45-degree offset sights or up as traditional sights. The other parts, pins, and springs to complete the build we also got from Strike, except for the ambidextrous safety selector from AIM Surplus. We also installed a drop-in trigger but found it wouldn’t ignite the hard primers in 7.62x39mm ammo roughly 5 percent of the time. We swapped in a crisp HIPERFIRE Eclipse trigger, setting up its springs to deliver more hammer energy than stock, and the problems went away. Finally, we always install a light and sling on rifles intended for use beyond competition. The SureFire M600DF scout light puts out 1,500 blinding lumens with its rechargeable 18650 battery, mounted in a slick Impact Weapon Components Thorntail2 mount, which pulls the light in tight against the handguard. A suitably austere but functional Proctor sling with QD swivels finished off the build. At the range, we tried eight different types of ammo, both domestic and imported. All ran perfectly, aside from the light strikes before we switched triggers. To assess accuracy potential, we benched it with a Nightforce at 40x — and it delivered 1 MOA five-shot groups with Federal’s Power-shok (the most accurate load in our 7.62×39 ammo roundup in Issue 26) and Winchester’s Super-X ammo. Who says 7.62x39mm can’t be precise? Other groups generally ranged from 1.5 to 2.5 MOA, and most loads posted average muzzle velocities just over 2,300 fps on our Magnetospeed chronograph (at 92 degrees F and 32-percent humidity). As usual, the Magnetospeed proved its worth, as we strapped it to the handguard and left it there during accuracy testing while simultaneously capturing velocity data. One item to note: BRS’s receiver is tuned specifically for Magpul’s MOE AK PMAGs, which ran 100-percent in our testing. Magpul’s Gen M3 magazines surprisingly have slightly different geometry and wouldn’t quite clear the mag catch to lock in place. Some steel AK magazines would lock in, but experienced some feeding problems. Bottom line — use MOE PMAGs with this gun, and it won’t let you down. Also, the bolt doesn’t lock back when empty, but neither do AKs. Weighing in at 9.3 pounds unloaded, the rifle handled beautifully and shot softer and flatter than we expected for a 7.62×39. BRS spent a lot of effort dialing in their system, and it shows. With the Eclipse trigger set at 3 pounds, we ripped off smoking splits with huge grins on our faces. This gun is a blast — we’re definitely taking it to some rifle matches. It turned out great, and we hope Mikhail would approve. Item & MSRP Billet Rifle Systems BRS-47 Receiver Set (Side Charging) $649 Billet Rifle Systems 7.62x39mm Bolt Carrier Group 200 Billet Rifle Systems Action Spring 20 Faxon Firearms 7.62x39mm 16-inch Barrel 185 Faxon Firearms Gas Block and Tube 46 SureFire 7.62 Muzzle Brake 149 Centurion Arms M-LOK CMR Handguard 240 Black Wood USA Wood Rail Panels and Handstop 115 Black Wood USA Featherweight Wood Grip 150 LAW Tactical AR Folding Stock Adapter 269 BCM Carbine Stock Hardware Mounting Kit 65 Mission First Tactical Battlelink Minimalist Stock 60 HIPERFIRE Hipertouch Eclipse Trigger 275 Strike Industries Lower Parts Kit 35 Strike Industries Enhanced Ultimate Dust Cover 16 Strike Industries Forward Assist 19 AIM Surplus AR Ambi Safety Selector 23 Burris XTR II 1-5x24mm Riflescope 959 Aero Precision Ultralight SPR Scope Mount 95 Strike Industries Sidewinder Backup Iron Sights 160 SureFire M600DF Scout Light 299 Impact Weapon Components Thorntail 2 Light Mount 50 Impact Weapon Components QD Sling Mount 19 Proctor Sling w/ QD Swivels 44 Magpul PMAG 30 AK/AKM MOE 14 Totals $4,156 Explore RECOILweb:Rare Spare Parts Community Gets Hi-Tech Upgrade With The Chop SwapUncle Mike's Tactical SweepstakesLangdon Tactical LTT Elite at NRA Annual MeetingsPreview - Latest In Collapsible Buttstocks NEXT STEP: Download Your Free Target Pack from RECOILFor years, RECOIL magazine has treated its readers to a full-size (sometimes full color!) shooting target tucked into each big issue. 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