The EMP (Enhanced Micro Pistol) 4" is a compact 1911 specifically engineered for 9mm — not a downsized .45 ACP, but a purpose-built 9mm frame with a 4-inch barrel. The EMP uses a smaller grip frame and shorter slide stroke than .45 ACP 1911s. Type: Pistol Action: Semi-Automatic Caliber: 9mm Capacity: 9 Year introduced: 2007, USA Weight: 26 oz Overall length: 7.5" Status: Active Intended use: Concealed Carry, Duty