I see everyone is spouting this BS again. Believe it or not, the caliber that AR's shoot (5.56 or .223) are actually far superior for home defense than any shotgun or handgun round because they don't penetrate walls as badly. Mind you, they can still go through like 3 or 4, but it's not as bad as buckshot or 9mm that can go through 5 or 6 walls. Plus, you have 30 rounds (depending on your state) which is far superior to any handgun or shotgun and it has significantly less recoil than 12 gauge. The only downside to AR's for home defense is they are extremely loud, especially indoors. So are handguns and shotguns, but they aren't quite so bad.
It's a semi-automatic man. It may be a little overkill. Semi-automatics are war machines.
Semi automatics have been around for over 100 years, they're not overkill, just the best tool for the job ---