>>64143373
The M16 was as much of a sidegrade to the M14 as it was an upgrade to the M1/M2 carbine or even the grease gun. Even adopting the AR10 and somehow bucking the Garand's built-in legacy, we would still be moving towards a universal infantry caliber like 5.56

>>63974623
M2 is a PDW. The M16 replaced it. At the time, the full auto M14 was an "assault rifle," in doctrine.