The 5.56 round was created to "wound", not kill because an injured soldier is a bigger drain on the enemies resource than a dead soldier.
The people arguing this will often say that the "enemy" will essentially lose 3 people for every wounded soldier, as they will devote two people to each one to care for them.
There are several holes in this argument. For starters, wounded soldiers can still shoot back!
Secondly, anyone who served in the military or knows people who served in the military can tell you that the US military is in the business of killing people. I've heard this from many people in the US military. My brother, who served in the USAF told me that one of his drill instructors made this point abundantly clear to them while in officer training. There is simply no way they would design a primary service rifle with the intent to merely "wound" the enemy.
Lastly, I cannot think of an enemy we have been at war with in the past 50 years that cared half as much for their wounded as our troops do.
For those of you not convinced, there's plenty of evidence out there that the 5.56 is an extremely devastating round, especially when it fragments.
You can see the wound profile of the original US military 5.56 round, M193.
Something many people don't realize is that the 5.56 is as devastating as it is when it fragments. Another thing they don't realize is that fragmentation does not always occur, even under ideal circumstances.
Just to demonstrate this, when shooting bare milk jugs filled with water, on a variety of occasions, I have noticed that although the 5.56 usually does fragment and breaks up in the 2nd and 3rd jugs, sometimes the round will just zip right through.
I have observed this in real life hunting when shooting coyotes as well. I have seen the rounds fragment (instantly killing the animal) and I have seen the rounds zip right through them. A good shot usually results in a kill either way though.
Just goes to show that there is no substitution for good shot placement!
For those who want to see the actual effects on human flesh with the M193 round, you can click on the link below.
WARNING - GRAPHIC PICTURES THAT MAY BE DISTURBING TO SOME VIEWERS - WARNING
That guy was lucky that he was shot in the leg. You can only imagine how things would have gone for that man had he been shot in the torso.
I will echo my previous comments, there is no substitution for good shot placement!
That said, myths like this die hard even when there are people out there spreading the truth. Hopefully we can help a few more people learn the truth. ;)