[2] These design features, rare in submachine guns, were chosen to enhance the safety of the user and to have a more reliable firearm.

[4] It features the SIG Sauer short stroke push-rod gas system to reduce the recoil and improve the reliability of the weapon.

[8] The MPX submachine gun is only available for military and law enforcement use, while a semi-automatic only version is also available for the civilian market.

[5] The standard MPX submachine gun comes with no sights and a full-length Picatinny rail system on the top of the weapon.

The MPX has a short-stroke gas piston system in order to increase the accuracy of the weapon which operates from a closed bolt.

[2] It is designed in this way to prevent water or dirt from entering the chamber and causing malfunctions as well as to use a suppressor with greater ease.

[15] As a result of this SIG has announced a carbine variant with a 406 mm (16 inch) barrel without the muzzle device, designated as the MPX PCC.