M-16
The M-16 is an assault rifle used by the United States military and others. It uses a slightly smaller cartridge than the M-14 and the AK-47, which was hotly debated at the time of its introduction. The smaller round allows more ammunition to be carried, and most battles are fought within its effective range. It is also easier to control in full automatic mode. The downside is that it does not penetrate through obstacles as well or cause as much damage when it hits. There are also arguments that the bullet tumbles and causes close to the same amount of damage.
The M-16 made use of innovative new plastic construction and was lightweight with a convenient carrying handle. Early models had problems with poor maintenance and jamming, but these were mostly worked out. It is now considered highly reliable, though not quite as indestructible as an AK-47.