The Rx4 Storm is a semi-automatic rifle developed and manufactured by the Italian Beretta company. It is from the same weapon designation system as that of the Beretta Px4 Storm pistol and Cx4 Storm carbine, although it is made with different working parts/design, and shares companionship only in name. The Rx4 Storm is a gas operated, rotating bolt rifle that uses an Auto-Regulated Gas Operation system originally patented by Benelli, makers of the popular M1014 semi automatic shotgun. It is chambered for the standard 5.56mm NATO round. Most variants of the Rx4 features a 16.2 inch barrel (the "Tactical" version used by Italian police has a 12.5 inch barrel and five point telescopic stock). Five round STANAG magazines are usually sold with the Rx4, and features iron sights.