For Home Defense

If you live in a condominium, apartment, or other densley populated area, I would suggest a .22 or a shotgun is well-suited to "home defense". If you have and must use an AR-15 to protect your family, the round you fire may well take down the assailant, but it may also go right through him and injure or even kill a neighbor. A shotgun might also be a decent choice as after a relatively short distance, the power of the pellets tends to diminish (presuming you are not firing slugs, which provide much more penetrating power than birdshot and even buckshot). Of course, the pellets also spread out which means you have to use extra caution in knowing your background if you must discharge your weapon. Of course, your great hope is the situation never arises that you have to protect yourself and your loved ones, but if you do, you must be prepared.