It's a sporterized military round, like the 308 and 223. They don't use just anything. It was well tested before they adopted it. It won 2 wars and would win a 3d if necessary. The only advantage the 5.56 has is that a soldier can carry a lot more of them.
“In a time of deceit telling the truth is a revolutionary act.” ― George Orwell
It's not over when you lose. It's over when you quit.
