I will disagree on the 5.56 as far as a house to house tool, and the 7.62 as a stopping round, in military configuration, the 5.56 is a better man stopper, in my opinion due to cartridge/bullet, velocity combo, but the 7.62 x 39, gets the nod for a lot more penetration, and I do mean a lot more. Accuracy with the 5.56 is easily 1/2 of the 7.62 round, in just about any platform, .5 too 2.5 moa, with a large amount of weapons and ammunition suppliers. 7.62 x39 is a 2.5 to 5.0 moa round in the rifles it is meant for, AK's, sks's, Valmets etc... But the bullet selection for the 7.62x39 is much more limited for defense use, there are premium ammo makers, providing excellent ammo for the 7.62, but it is at a premium price, Hornaday TAP, Winchester hollow points, etc.. would be excellent anti-personnel rounds but the cost would be prohibitive. If it was my main defense rifle, I would make use of this ammo, but buying a case would probably prevent ME from doing it. I own both, and do not discount either caliber, The penetration, of the 7.62, I have witnessed, and in a street fight I would find superior, when firing at vehicles, or windshields, or anyone taking cover, behind what we call hard cover. Don't tell anyone, ( yeah right ) but I shot a dumpster longways, and the fmj, penetrated the very thick wall on one side and goose egged the hell out of the other side. The 5.56 might have barely penetrated the first wall, and only with tungsten core ammo, unless, I had been very close, and still the bullet would not have done any damage after penetration.
I will continue to use the 5.56 as my sort of primary defense round in my own domicile, but the 7.62 is always near and dear. Of course this does not address main battle rifles at all.
Of course, the minute of angle, inside 100 or 200 meters, of 2.5 to 5.0,, is completely acceptable, and I don't feel underarmed with either, caliber.
Let the discussion begin !