It has been my experience that the 5.56 lacks what it takes when you need all you can get, nuff said.
Remember it was designed to be a wounding cartridge, unfortunately our enemies have devolved to where they do not give a dam about their wounded, their wounded would probably be shot by their own. So its usefulness as a strategic weapon that was supposed to tie up their hospitals with wounded does not come into play any more.
For close quarter work I’ll use a 5.7x28
I have heard it can be necessary to double-tap with a 5.56 ... though it can also be necessary with a 7.62, and you have fewer rounds. I thought Special Forces operators used primarily 5.56. For instance, the weapon that supposedly got OBL was an HK416, which I thought was a 5.56 weapon. Maybe I’m mistaken.
For me, it is primarily a target shooting and CQC self-defense weapon. I don’t imaging I’m going to be doing much long-distance self-defense shooting.
SnakeDoc