Once upon a time I hit a 110 pound guy, with an AK and blood in his eye, with three rounds of 5.56mm ball. Didn't slow his ass down one bit. He was on a mission to kill me. Drew my 1911 and put two in his chest at 50 feet. Dropped him in his tracks. Upon examination of the body it was clear the ball had penetrated his upper chest around the shoulder but had not done much damage. The 45 tore massive holes in his heart and one lung.
Now I still have faith in 223/5.56 but I do not use full mags of ball.