The first rifles did not have forward assist. McNamara intervened several times in the M16 fiasco. The Army made its boo-boos too. The Army decided to substitute ball powder for the IMR powder used in testing the rifle. That ball powder increased the cyclic rate of the weapon by about 200 rounds per minute; causing accelerated wear. The ball powder burned dirtier than IMR powder; quickly crudding up the rifle. In about 1966-67 the Army went IMR powder and some of the problems with the M16 went away.
http://www.gundigest.com/article/the-ar-16m16-the-rifle-that-was-never-supposed-to-be/7
My brother deployed with the 2/7 CAv, 1st Cav Division to RVN in 1965. Soon after reaching Viet Nam; the 2/7 Cav was issued M16 rifles. No cleaning equipment was issued with the rifle.
McNamara personally intervened when the Army tried to issue cleaning equipment with the M16 rifle. Stoner claimed the M16 was "self cleaning" and that was good enough for McNamara. i sent my brother a cleaning rod, brush, solvent and patches. My brother was killed at Ia Drang on 17 November, 1965.
For decades my burning desire was to piss on the grave of Robert Strange McNamara. Then the sonofabitch was cremated. i'll settle for pissing on the grave of Rumsfeld.