Benelli’s M4 Tactical is a unique Auto Regulating Gas-Operated (A.R.G.O) semi-automatic shotgun, upon which the U.S. Marine Corps  depends. The M4 Tactical comes standard with a Picatinny rail and  tactical stock. Other features include a fully adjustable ghost-ring  aperture rear sight and windage-adjustable front sight. The M4 is  also available with a durable, weather-beating Titanium Cerakote finish.