The M4 shotgun, abbreviated as M4 shotgun, is a semi-automatic shotgun designed and produced by the Italian company Benelli. This firearm is renowned for its excellent performance and high reliability, originally developed as a tri service combat shotgun for the US military. The M4 shotgun is capable of firing 2 3/4 inch and 3-inch 12 gauge shotgun shells, utilizing a unique "automatic adjustment pneumatic operation" system to ensure stable performance in different environments. Its design includes two small stainless steel pneumatic pistons, installed at the front end of the handguard to facilitate the normal operation of the bolt action gun. Widely used in various US military units, it has proven its outstanding performance in actual combat.