Well considering the early M16's didn't have a forward assist, crome lined bore, and weren't issued with a cleaning kit, not to mention that the Army Ordinance folks decided to use stick powder instead of the recomended ball powder in the ammo the rifle got a bad rap in it's early days in Vietnam.
In my 17 years in the military and with the personal AR-15 I own I've probably fired well over 100,000 rds and I remember 3 malfunctions that I've had. 1 was due to a bent lip on the magazine, 1 was a pop no kick (no powder in the round) and I had a double feed once.