Wow. So if I brought a long rifle into your neighborhood and start aiming it at people on the street and you tried to disarm me, I can shoot you dead and call it self-defense? And if your friend hits me in the head with a skateboard and I kill him too, that is self-defense? And after I shoot you, if your neighbor draws a hand-gun on me, I can shoot him too and call it self-defense?
Who is the initiator here? Did anybody shoot at me before I began the killing?
Leave it to the police, who wear obvious and recognized insignia of authority. Otherwise, you’re just a loose cannon rolling around on the streets.