A self defense rifle has to perform the first time, every time. The ultra-reliable A.R.G.O. system incorporated into the new Benelli MR1 does it for the U.S. military, and makes the MR1 the best home defense rifle available. The MR1 self defense guns are chambered in .223 Remington and use the battle-proven Auto Regulating Gas Operated System, the same system developed by Benelli for the M1014 (M4) and used for over a decade in multiple conflicts by the United States Marine Corps. The MR1 features a stainless steel, self-cleaning piston that operates directly against the proven rotating bolt, thereby eliminating the need for complex linkages found on other, inferior gas systems. This piston-driven system, perfected by Benelli, incorporates a gas port located just forward of the chamber, where the gases are hotter and cleaner, resulting in less fouling and more reliable cycling. Accepts high capacity M-16/AR-15 magazines.