Oh boy, are you misinformed! Yes, AKs have an edge in sand worthiness, but M-16s work fine too if kept clean. As far as ammo interchangeability, NO! This is like saying, "I'm pretty sure BMW engines are interchangeable with Toyotas."
But to match up AKs vs M-16s, you must above all compare accuracy. At 100 yards and beyond, there is no comparison at all. A taliban with an AK who is 200 meters away from an American soldier with an M-16 is dead meat. He'll never get close enough to demonstrate the AK's great reliability.
Wouldn’t want to shoot a 5.62mm round into a 5.56mm barrel!