Beretta Cx4 Storm The Beretta Cx4 Storm is a pistol - caliber carbine aimed at the sporting , personal defense and law enforcement markets . Seven different models accept full - size Beretta magazines from the 92 / 96 , Cougar , and Px4 series pistols in 9x21 IMI ( its original caliber ) , 9x19mm Parabellum , . 40 S & W and . 45 ACP . The Beretta Cx4 Storm is the civilian version of the Beretta Mx4 Storm . Design details . The Cx4 Storm was developed to be used in conjunction with Beretta semi - automatic pistols . For example , the magazines for the Beretta 92FS chambered in 9mm can be used in the Cx4 ( also chambered in 9mm ) . This aids in a smaller loadout – no longer needing to carry separate magazines for the rifle and handgun – and adds redundancy , allowing a person to carry more ammunition without adding weight . Conversion between Px4 Storm , 92 / 96 and 8000 / 8040 Cougar 9x19mm Parabellum / . 40 S & W magazines requires two parts ( not included with rifle ) . For Px4 magazines the C5C620 magazine insert and C89210 magazine release button are required , for 92 / 96 the C5A511 insert and C89109 release , for Cougar the C5A670 insert and C89110 release . The . 45 ACP model only accepts 8 round single stack 8045 Cougar magazines . 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 , bipod s etc . This firearm was designed to be very adaptable to customization . The Cx4 comes from the factory with adjustable iron sight s . 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 . 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 . In addition to being able to customize the Cx4 with accessories , it is one of only a few firearms with the ability to switch the safety , cocking handle , ejection port , and magazine release to the left side of the weapon to accommodate left - handed shooters . Dawson College shooting . The Cx4 Storm was the primary weapon used in the 2006 Dawson College shooting . The gun had been acquired legally , and calls were later made to ban its sale in Canada . Sales of the weapon in Canada increased following the shooting .