The M16A1 is a variant of the M16 rifle and was the first major iteration widely issued to the U.S. military during the Vietnam War. Below is a detailed overview: Overview \t•\tType: Assault Rifle \t•\tCaliber: 5.56×45mm NATO \t•\tAction: Gas-operated, rotating bolt \t•\tRate of Fire: 700–900 rounds per minute \t•\tEffective Range: 400–500 meters \t•\tMagazine Capacity: Typically 20 or 30 rounds (STANAG magazines) \t•\tWeight: 6.5 lbs (2.94 kg) unloaded History \t•\tDevelopment: The M16A1 was an