The Beretta Cx4 Storm is a pistol-caliber semi-automatic carbine version of the Rx4 aimed at the sporting, personal defense, and law enforcement markets. It is available in two models: one that accepts 92/96 magazines, and one that accepts Px4 series magazines, each available in 9×19mm Parabellum, .40 S&W, .45 ACP, and 9×21mm.
The CX4 Storm includes a Picatinny rail that can be extended under the barrel by pushing in the sling button and pulling the rail out by a thumb tab. Each Storm also includes a side rail with two mounting screws, a second can be purchased along with a bottom rail from the manufacturer. The contoured bottom rail is designed to attach under the two side rails. A top rail can also be purchased and installed with a tool that comes with the carbine. Three screws and nuts attach it to the top of the carbine using a pre-drilled hole, allowing the user to use the rail as a template to tap two other holes hidden under a thin membrane of plastic. The correct size drill bit needed for attaching the top rail is not included with the rifle or the top rail kit and has to be purchased separately. A maximum of five Picatinny rails can be utilized using Beretta accessory kits, or the user can use the two present at purchase to attach a number of optics, grips, lights, lasers, bipods etc. This firearm was designed to be very adaptable to customization.
The Cx4 comes from the factory with adjustable iron sights. The front post sight is adjustable for both windage and elevation using the supplied adjustment tool. The rear flip sight has two apertures for snap shooting and long-range elevation selection. Both sights can be folded down when optics are mounted to the optional top rail.
The stock on the Cx4 has an adjustable length of pull. Adjustment is made by the use of stock spacers. The carbine comes with one spacer installed, which may be removed. With no stock spacers installed the minimum length of pull of the Cx4 is 337 mm. To increase the length of pull, additional stock spacers may be purchased separately. A total of three stock spacers may be installed which bring the length of pull to a maximum of 382 mm.