The M16A1 is the first standard military production version of the AR-15/M16 platform, incorporating lessons from early Vietnam fielding: chrome-lined bore and chamber, forward assist, birdcage flash hider, and improved buffer. It replaced the M14 as the US standard infantry rifle and has been the basis for decades of military small arms development. Type: Rifle Action: Semi-Automatic/Full-Auto Caliber: 5.56x45mm NATO Capacity: 20 Year introduced: 1964, USA Weight: 6.35 oz Overall length: 39" Status: Discontinued Military use: Yes Intended use: Military