I'm wondering about a couple of his (akados) remarks.

you said that SMG rounds weigh more than AR rounds? i'm not saying it ain't true, but looking at the volume/mass of a SMG/pistol round say a 9mm vs a 5.56mm Nato AR round.. well the AR round is a little less large in the diameter but is FAR taller. and though the actual bullet is again less in diameter it is also longer or seems that way visually. do you have any good links on the weight of rounds?

in your #4 you state that an ar is better because it penetrates better.. does this not esp in CQB actually become a penalty. Shooting through multiple walls and hitting civvys or flamable objects or other members of your team etc.