A break in would be acceptable use in terms of permission. Taking a gun out and confronting the neighborhood ne're-d'ells who are walking down the street and yelling would not.
The original poster specifically asks about blowing away bullies on the property. The way he seems to phrase it he would run inside, get the gun, run back out and shoot. Seems to me running inside, locking the door, dialing 911 and waiting with the loaded gun would be appropriate as there is no longer an immediate threat but only a potential threat . . . until someone comes through the door.
Well, yeah, but that applies equally well to adults as to minors.
Incidentally, Indiana Law (I'd have to look up the relevant section) includes "curtilage" (fancy word for "yard," more or less) in the area in which one has not duty to retreat and in which deadly force is authorized to prevent unlawful entry. However, per Ciyou's book, the case law on that is a bit thin and actually shooting someone on the basis of that alone, without other factors making the threat real, would be legally rather dangerous.