The Benelli M4 Tactical Shotgun has truly earned the title: The first tactical shotgun. The Benelli M4 Tactical Shotgun uses a semi-automatic operation first developed by the US Army Armaments Research called, ARGO- Auto Regulating Gas Operated. Benelli’s version of ARGO utilizes only four parts, making it simple and extremely reliable.The Benelli M4 Series is a modular firearm, meaning the operator can easily replace various assemblies (Barrel, Buttstock, and Forearm) without the use of tools. This allows for easy service and extended reliability in the field.The M4 Series uses a standard (MIL-STD-1913) Picatinny rail that allows the adaptation of standard optics as well as retains the original sights.As an added option Benelli has added the H20 Coating. Benelli M4’s with this option are even more protected from the elements: whether it’s marine salt spray or desert sand.