Heckler & Koch MP5. This submachine gun was seen in the hands of counterterrorist units prior to Doomsday. It made its famous debut during the 1980 Iranian embassy hostage crisis in London where it was seen in the hands of SAS operators. Since then, the MP5 has defined the generation of submachine guns. Even after Doomsday, the MP5 is still in use by surviving military and law enforcement units around the world.