"As a tanker, I was issued an M9 submachine gun. And let me tell you, the M9 was a gun that wouldn't fail you. It's so simple that it makes an AK-47 look complicated. The only moving part is the bolt. It won't win any shooting competitions, but it'll never fail you."
-Lt. Victor Cruz, Paternian Marine Corps, 11th Expeditionary Division

The M9 Submachine Gun is a Paternian-designed submachine gun designed to provide a cheap, reliable, and powerful automatic weapon. Virtually every single component, save for the bolt and the barrel, can be made by stampings, and the bolt can be cast. Although a .45 caliber weapon, all that needs to be changed to fire 9mm cartridges is to change the magazine and barrel.

Able to serve .45 caliber bullets at 600 rounds per minute, it is highly controllable in the process. Although dated when compared to more modern automatic weapons, it still sees use in the Paternian Armed Forces as a vehicle crew sidearm for those issued with .45 caliber pistols. In addition, it sees use with some specialist Paternian Gendarme units.

While the weapon sees extensive service with legitimate forces, it also has a criminal element within; cheap copies of the M9 is often seen in the hands of criminals and terrorists, given the weapon's simplicity and low cost.