Benelli's A.R.G.O. system is a unique, short-stroke, dual-piston design incorporated into the M4 Tactical shotgun that makes it self-cleaning and exceptionally reliable. As a result, the M4 Tactical was selected for service in the U.S. Marine Corps. It was later adopted as the U.S. Joint Services combat shotgun-and remains so today. This superior semi-automatic shotgun has been battle-tested in combat theaters around the world, and it is known for its durability and effectiveness in a wide range of field conditions. The M4 Tactical incorporates the latest Benelli shooting technologies for optimal shooter comfort and recoil reduction. 7 Round capacity. This piston-driven A Mfg: Benelli