Amazingly, considering the storm of controversy which surrounded the light rifle program in its early days, the M16 has gone on to become the longest serving light rifle in U.S. history. The M16 today is at the centre of a thriving, multi-million dollar industry involving a number of companies and military agencies who are designing and manufacturing drop-in upper receivers in various configurations and calibres, plus complex rail systems and other high tech accessories, all based on the M16 platform, which grows more firmly established. This book covers the new third and fourth generation rifles and carbines that have been introduced by both Colt and Diemaco, and describes the enhanced sights and rail systems which helps the M16 of today one of the most versatile, modular combat weapons in the world. It also covers the colt semi-automatic only family of commercial and law enforcement products, in .22 Remington, 5.56mm, 9mm and 7.62x39mm, and it has an in-depth component guide covering all the military and civilian variations of the M16