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. MR1 self defense guns are chambered in 5.56 mm NATO (.223 Remington) and use the battle-proven Auto Regulating Gas Operated (ARGO) 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.
Seems like Benelli needs a heads up in their ads. Chambered for 5.56 but barrel says .223 only, odd.