40 S&W magazines requires two parts (not included with rifle). 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.Ĭonversion between Px4 Storm, 92//8040 Cougar 9×19mm Parabellum/. For example, the magazines for the Beretta 92FS chambered in 9mm can be used in the Cx4 (also chambered in 9mm). The Cx4 Storm was developed to be used in conjunction with Beretta semi-automatic pistols.