Complex sentence: Eugene Morrison Stoner (November 22,1922--April 24,1997) is the man most associated with the AR-15 rifle, adopted by the US military as the M16.
Split into simpler sentences: Eugene Morrison Stoner (November 22,1922--April 24,1997) is the man most associated with the design of the AR-15. It was adopted by the US military as the M16.