The M4 is a shotgun of Italian origin. It was developed in the late 1990's by Benelli at the request of the US Marine Corps. The M4 looks similar to the earlier M3 Super 90 but differs in its internal mechanism. Since both weapons have different characteristics both remain in production.

The M4 looks rather similar to the M3 Super 90, but differs in having a gas system instead of the inertia driven system. The double gas piston setup makes the M4 cycle more reliable in arduous circumstances and with multiple attachments, but dispenses of the pump-action ability. A Picatinny rail allows optics to be fitted. The M4 is also fitted with a retracable stock and pistol grip as standard, although a fixed stock is available.

The M4 fires 12ga shells with a length of up to 3 inch. The standard version has a 7 round tubular magazine while the shorter barrel M4 Entry has a 5 round one. The gas system will also cycle mild buckshot loads, but most non lethal rounds will not. The effective range is givens as 35 meters. Since the barrel is not rifled the use of slugs is limited to a few dozen meters.

The M4 is one of the more common tactical shotguns in the world. The primary user of the M4 is the US Marine Corps with over 20.000 purchased. It is widely used by law enforcement teams and counter terrorist units, mainly in the USA and Europe. It remains in production besides the M3 Super 90 which uses a different mechanism.