M16 uses special 5.56mm high velocity round that breaks up / explodes upon entering flesh, causing horrific wounds. As some one puts it, there is no one hit by a M16 round that's still walking around. The AK47 round is slower and does not break up, the wound is less severe. However the Russian 5.45mm round used in AK74 has the same characteristics of the NATO 5.56mm round, and will cause more damage than the M16 round. Both rounds have been tested in battles, both were satisfactory. The Chinese 5.8mm round has not been battle tested, however I would imagine that it will cause no less damage than the previous two.