The Windham R16M4 is a mil-spec AR-15 carbine with a 16-inch M4-profile chrome-lined barrel, representing Windham's straightforward take on the M4 configuration without frills at a competitive price. Type: Rifle Action: Semi-Automatic Caliber: 5.56x45mm NATO Capacity: 30 Year introduced: 2012, USA Weight: 62 oz Overall length: 32.5" Status: Active Intended use: Tactical, Home Defense