Aero Precision manufactures AR-15 receivers and complete rifles in Tacoma, Washington. The M4E1 uses Aero's enhanced receiver set with a threaded barrel extension and proprietary Handguard Attachment System (HAS) making the free-float handguard stronger and more consistent than competitors. Aero Precision is one of the largest US AR component manufacturers by volume. Type: Rifle Action: Semi-Automatic Caliber: 5.56x45mm NATO Capacity: 30 Year introduced: 2016, USA Weight: 92 oz Overall length: 35" Status: Active Intended use: sporting, tactical, law_enforcement