When the U.S. Marine Corps went shopping for a combat shotgun, they bought a Benelli. That’s because a combat shotgun has to function the first time, every time. The Benelli M4 does it for the U.S. military Benelli engineers developed and patented a unique auto-regulating gas-operated (ARGO) system. Dual stainless steel, self-cleaning pistons located just ahead of the chamber operate directly against the bolt assembly. It’s a simple and dependable system that eliminates the complex linkage, springs and heavy parts that other semi-automatic shotguns have to depend on. The result: Marine-tough reliability under the harshest environmental conditions.The M4 comes standard with a Picatinny rail for optics, a ghost-ring fully adjustable rear sight and fixed blade front sight; a variety of modular stocks are available as accessories. The M4 is combat proven and U.S. Marine Corps approved — why would you depend on anything less?