The M16A4 served as the primary service rifle for the US Marine Corps from 1997 until 2015. -Essentially an M16A2 with a flat-top receiver and a MIL-STD-1913 rail system, it allowed for the mounting ...

But the advent of modular rail accessory systems and the growing use of optics over iron sights added more weight. The long length of the M16A4’s rail systems adds a great deal of weight for ...