The M16A2 introduced the NATO-standard SS109/M855 ammunition, a heavier 62-grain bullet requiring a faster 1:7 twist barrel. Added a burst-fire mode replacing full-auto, heavier barrel, improved sights with windage adjustments, and a stronger handguard. Type: Semi-Auto Rifle Action: Gas-Operated Caliber: 5.56x45mm Capacity: 30 Year introduced: 1982, USA Weight: 8.8 oz Overall length: 39.6" Status: Discontinued Military use: Yes Intended use: Military, Service Rifle