The M16A1 is an assault rifle of US origin. The M16 was a giant leap forward in firearms design and the first standard issue assault rifle adopted by US forces. The M16A1 is the first generation of the M16 family. It was used by US forces throughout the Vietnam War. It proved to be a promising weapon, but suffered from a number of flaws, which were remedied in the later M16A2.
The M16 has a conventional layout while the M16 seet the standard on what is nowadays called a conventional layout. The M16 is based on the straight line principle. The shoulder stock, action and barrel are all in one line resulting in reduced recoil. In order to aim properly the sights have been raised. The rear sight base also functions as a carry handle for the weapon. The receiver is made of aluminum with the barrel, bolt and other parts in the mechanism made of steel. The forearms, pistol grip and stock are made of plastics. The M16 uses direct impingement gas operation. When a shot is fired high pressure gasses build up in the barrel. In the M16 these gasses are tapped via a port in the front sigh base and through a gas tube above the barrel they cycle the system. This design reduces the amount of moving parts significantly, but the gasses foul the moving parts easily. All variants are based on the same design the barrel, forward assist and stock and forearm may differ per version.
The M16A1 fires the 5.56x45mm round which was specifically designed for this weapon. For a long time the M16 was issued with 20 round magazines as the development of a 30 round magazine proved difficult. A slightly curved 30 round magazine proved to be the solution. The M16A1 is a select-fire weapon with a cyclic rate of fire of 700 to 900 rounds per minute. The maximum effective range is 400 m for the M16A1 and 300 m for the CAR-15. Overall the M16A1 is a good rifle. It is very light, accurate, ergonomic and has a very low recoil. The main drawback is its lack of reliability. When properly cleaned the it will function well, repeated cleaning is needed in moist and arid conditions.