SIG Sauer developed its MPX to be the ultimate pistol-caliber platform on the market, designing the system from the ground up to withstand punishment while feeding and firing rounds without any hiccups. Each SIG Sauer MPX is purpose-built to offer a compact, modular firearm to consumers and professionals alike, and the gun is trusted by law-enforcement and military units across the world. Barrel length: 4.5 inches Overall length: 21.75 inches Chambered in 9mm Ships with one 30-round magazine To ensure reliability, the gun uses a gas-operated mechanism, and the gun's unconventional design ensures it'll keep running when other subgun-style options on Mfg: Sig Sauer, Inc.