1. Get a double barreled 12 gauge shotgun.
2. When faced with possible threat in your home, walk outside onto your porch with double barreled shotgun.
3. Fire both of your shells into the air as a warning shot. No aiming required.
4. You are now safe.
5. You do not need an AR 15 because the above method is proven effective, and the AR 15 requires aiming.