by Shooting Illustrated Staff posted on October 21, 2010 Guns Support NRA Shooting Illustrated DONATE 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 Review: Staccato C Pistol First Look: Wilson Combat Division 77 Project 1 What's the Best 38 Special Ammo for Self-Defense? The Ultimate Home Defense Shotgun First Look: Ruger RXM Pistol Best Distance to Zero a Pistol-Mounted Red Dot