by Shooting Illustrated Staff posted on October 13, 2011 Guns Support NRA Shooting Illustrated DONATE ** When you buy products through the links on our site, we may earn a commission that supports NRA's mission to protect, preserve and defend the Second Amendment. ** Primary Weapons Systems goes out of the box in AR design. In this article 5.56 NATO, 7.62 NATO, AR, Primary Weapons Systems Related Stories Primary Weapons Systems PWS MK116 and PWS MK216 Carbon-Fiber Rifle Round-Up Gemtech Suppressed Bolt Carrier AR-15 Muzzle Brakes 14 New Rifle-Caliber Pistols for 2019 Most Popular CZ to Supply Pistols to the German Army 10mm vs. .40 S&W: Similarities, Differences and Uses First Shots: Springfield Armory Hellcat OSP .380 Marines Ditch 100-Year-Old Marksmanship Standards First Look: Ruger Red Label III Shotgun Top 5 'Budget-Priced' .50 BMG Rifles