I am with Electric Insurance. Under the exclusion section, it includes text "does not apply to bodily injury resulting from the use of reasonable force by an 'insured' to protect persons or property".
Common Law self-defense would apply here I assume. At least it gives the exclusion for BOTH persons and property. If someone enters my house by force and is armed, I can use reasonable force with a firearm to stop him since my life or my families is in immediate danger. If someone enters my house by force and is unarmed, I assume firearm use would not be considered "reasonable", unless he tried to attack me or my family.
Gene G can weigh in on this for sure.