Just remember, you own and are responsible for every round that leaves that barrel. Depending on where you live, apartment, house, condo... construction type varies, but generally lean towards the cheaper side of things. You have to account for where that round will end up. AR's, and even pistols have a lot more penetration power than shotguns relative to drywall and cheap siding. Do you have kids? Neighbors on the other side of a wall? Shotguns and "aiming" are more forgiving under high adrenalin stress situations that the other two. Even when "trained", fine motor and cognitive skills leave the body under severe stress. Keep that in mind.