by Shooting Illustrated Staff posted on October 21, 2010 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. ** Benelli MR1 In this article 5.56x45 mm, Benneli, semi-auto rifles Related Stories DPMS Panther 3G1 Gallery DPMS Sportical Gallery The Truth About Pistons Barrett REC7 Chambered in 5.56 NATO Gallery Auto-Ordnance AOM160 M1 CarbineAuto-Ordnance AOM160 M1 Carbine Gallery Most Popular 10mm vs. .40 S&W: Similarities, Differences and Uses CZ to Supply Pistols to the German Army First Shots: Springfield Armory Hellcat OSP .380 First Look: Wilson Combat Division 77 Project 1 Ghost Pistol Top 5 'Budget-Priced' .50 BMG Rifles Marines Ditch 100-Year-Old Marksmanship Standards