Aero Precision M4E1 Enhanced in pistol configuration with a 10.5-inch barrel and SB Tactical brace, offering enhanced furniture and ambi controls in the NFA-exempt pistol format. Aero's most complete factory pistol AR. Type: Rifle Action: Semi-Automatic Caliber: 5.56x45mm NATO Capacity: 30 Year introduced: 2019, USA Weight: 88 oz Overall length: 23.5" Status: Active Intended use: Home Defense, Competition, CQB