which is the best round for CQB. I've done the research myself. You should look into it. There are people on both sides, but the evidence is clearly favorable to the AR-15. Look up some of the ballistics tests conducted by Dr. Martin Fackler.
There is a reason that police and SWAT teams are dropping pistol carbines like the MP5 and shotguns for the AR-15.
People who say the AR-15 is bad for home defense are stuck in an old way of thinking. They may as well think the world is still flat.