"Ah, but now you're getting into "knockdown power" or "stopping power", not simply "lethality". I would bet that the overwhelming majority of people who take a solid torso hit from a NATO 5.56 round will die in short order (<30 minutes) without competent medical attention. That makes it "lethal" in my book.'
Knockdown power is a myth. NO bullet can knock you down. If it could, the guy firing it would also be knocked down.
And you would LOSE that bet (and your life) if you were shooting at skinnies in Somalia.
The simple fact is NO weapon is a "death ray", no matter how many "+s" you have in front of it's caliber.