The United States Marine Corps adopted the Benelli M4 Super 90 in 1999. Since then it has quickly become the most popular combat shotgun in the world.
LEO and military versions of the M4 feature a three-position collapsible stock, but civilian models are fixed stock only.
The M4 was Benelli’s first attempt at a gas-operated shotgun using an “auto regulating gas operated” (ARGO) system using just four parts: two shrouds holding two gas pistons.
More rugged than most semi-auto shotguns, the M4 can function reliably over at least 25,000 rounds without replacing any major parts.
See the M4 in action with legendary speed shooter Jerry Miculek in the video below