For a firm recognized globally for its excellent semi-automatic handguns and long guns, SIG-Sauer turns heads with its introduction of the SIG MPX series automatic weapon. The type can fulfill the roles of machine pistol, submachine gun and carbine through its inherently modular design approach. Full support of tactical accessories and the robustness and reliability of the SIG-Sauer brand label make the MPX a serious competitor in the small-caliber marketplace - general dominated by AR-15 clones and the German Heckler & Koch HK MP5 family of automatic guns.
The weapon is recognized as the first of its kind to sport a fully-enclosed rotating bolt and pistol system to increase general operating safety and reliability.
Four major models are marketed: the MPX (standard), MPX-K (compact), MPX-P (machine pistol), MPX-SD (supressed model), MPX-PSB (machine pistol) and MPX Carbine (assault carbine form). Are all in 9x19mm Parabellum chambering though some limited to Semi-Automatic-Fire-Only (SAFO). Weight differs between each mark as does dimension and stock type fitted.
The grip has an AR-style ambidextrous control scheme (selector and magazine release) to support both left- and right-handed shooters. The action has a bolt hold-open feature to indicate last-round-fired and the bolt-release sports an ambidextrous design quality. Additionally, the rotating bolt system is fully-locked and closed to help protect against a bullet obstruction or water entry in the bore. The gas-operated, short-stroke pistol within is designed to reduce the inherent recoil and general fouling consistent with repeated firings. The magazine well is beveled and flared for ease-of-reloading for "sight-unseen" operation. Sections of Picatinny rail are set over the length of the receiver and handguard, under the handguard and along the sides of the handguard for the fitting of various tactical accessories - optics over, foregrips/flashlights/aimers under and any other assisting product along the sides. For further customizability, the barrel length and stock can be reconfigured by the operator in-the-field.
Optional features include 10-, 20-, and 30-round curved detachable box magazines and integral QD sling point loops. The stock can be removed for a shorter overall profile or a telescoping version installed in its place. Additionally, a folding stock is offered for that "truer" tactical appearance. The handguard has rail-adaptable sections of aluminum or carbon fiber construction. The upper receiver is monolithic (formed from a single large piece) set over a free-floating barrel and has an integral M1913 rail as part of its design. Barrel lengths are adjustable for 4.5", 6.5" and 8" lengths.
It is planned that the MPX will eventually support .357SIG and .40 S&W chamberings through after-market conversion kits.