I dont know jack about ARs, but I do know that a .223 / 5.56 NATO is one of the most combat proven rounds around. It does its job. It takes the target out, can shoot through walls and is highly accurate at typical combat ranges. There are literally thousand upon thousands of people who have been killed or wounded by this round and that it has dominated the battlefield for a long time. Nothing lacking in a .223. Just because its a similar diameter, doesnt mean its ANYTHING like a .22 ....
"They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety. - B. Franklin"