At the 2013 SHOT Show, SIG Sauer released the innovative MPX submachine gun. This year, Mark Keefe got to give it a test run at the range on Media Day. To see how it ran, see the video below. The MPX is a modular, multi-caliber SMG that was designed for military and law enforcement. This submachine gun features a SIG Sauer short stroke pushrod gas system and a closed, fully locked rotating bolt system. For more information, visit SIGSauer.com.