The only real knock against the AR for home defense is the potential for overpenetration. Because if you shoot and don't hit something soft and fleshy, the bullet's liable to go through four or five walls, exit the house, fly all the way to the neighbor's house and kill him, his wife and their two dogs.
Me, I
want overpenetration. It's one of the top reasons I have an AR for home defense. It's been a long time since I got paid to kick in doors so I'm inclined to leave that to the professionals. There's no material thing in my house that's worth losing my life over and the most valuable stuff is in the room where I sleep. And you don't get extra points for exposing yourself to the intruder and if you get killed in the process, you're still dead. So if there's a bump in the night and I suspect it might be seriously dangerous people, I'm grabbing my phone and my AR and rolling off the bed on the side
away from the bedroom door.
Then I train my rifle on the door (using the bed for a rifle rest and cover) and call the police. Tell them what's going on, what room I'm in and where in the flower bed my extra key is hidden. Then I wait for them to come and let themselves into my house and run the mook off. Or kill him, their choice.
In the meanwhile, I'm armed to the teeth and I know the invaders can't get to me except through that door, nor do they know for certain where I am. And my hall floor squeaks. And I haven't fixed it so it serves as an early warning system, like
a nightingale floor. If the floor squeaks outside that door, I'm going to run a beta-dump through that door and the first 10 feet of the hallway. Then load the
second magazine ... and listen. If there's anybody out there still alive after that hail of gunfire, I'll shake their hand and buy 'em a Daniel Webster seegar.
Which is why my AR is loaded with 64-grain Speer Gold Dots, because they're barrier-blind, intentionally made so they'll go through the first wall and still do the business. The poodle-shooter AR's lethality is all tied up in bullet fragmentation, but if the bullet fragments on the bedroom door, then nothing but splinters gets to the mook outside. So I'm loaded with barrier-blind ammo.
But that's my plan. You need a plan. Buying an AR doesn't automagically make your home safe from invasion. You have to have a plan that the AR works within. And an AR is a machine. You'd be a fool to buy a machine that you might have to trust your life to and not get training on how to operate it.
Which is one reason I don't recommend an AR as a first gun. Everybody's first gun (or
only gun, if your a one-gun home) should be a .38 or .357 SA/DA revolver. Because the ammo is available anywhere they sell bullets, and it's the most goof-proof repeating firearm in existence. There's only one immediate action item for a stoppage. Pull. The. Trigger. Again. All detachable magazine autoloaders are subject to
four different kinds of stoppage and have three different immediate action items, depending on the type of stoppage. So not only do you have to recognize the nature of the stoppage, you have to select the correct immediate action for that particular type. Or you could just swing it like a club.
Revolvers are just easier.