Open your front door and step out onto the front porch or stoop with your favourite open carry rig on your hip. Do not point to it. Do not let your hand go to it. Do not refer to it or mention it in anyway. As someone said before, give them one warning. "Disperse from my property and leave me in peace. This is your one and only warning. Any resistance or delay will result in the police being called to deal with your disturbance of the public peace." Go back inside and watch their antics on your video security system. If they're all gone in 3 minutes, call it even. If they're not gone in 180 seconds, follow through and call the cops. Do not open the door again until it is an officer. Answer the door with the same open carry rig, because you know the idjits will claim you threatened them with it. Let the cop see (but not disarm you) what they saw.
When they "Nudge. Shove. Shoot.",
Don't retreat. Just reload.