The Aero Precision M4E1 5.56 Pistol is a compact pistol-configuration AR built on the M4E1 upper, offering Aero's tight tolerances and improved handguard interface in a short-barrel package. Type: Pistol Action: Semi-Automatic Caliber: 5.56x45mm NATO Capacity: 30 Year introduced: 2016, USA Weight: 52 oz Overall length: 26" Status: Active Intended use: Home Defense, Tactical