Attacking somebody with a firearm and defending yourself with a firearm are two totally different things. No wonder you are so confused.
The guy who burst in
was defending himself.
He wasn't going to shoot anyone until the householder reached for a weapon.
No, he had every intention on shooting somebody and put himself in that position. Much different than when you are minding your own business and somebody attacks you. Self-defense does not mean attacking another person. Look it up in the dictionary or on Wiki.
Well...if you really want to you can ignore police instructions, track down a teen ager, pick a fight with him then kill him and get away with it. If you don't believe it ask the piece of shit George Zimmerman....the guy who shot Treyvon Martin. That useless bastard has been in and out of trouble several times since that happened. He was a cop wannabe.
Once again, learn the difference between being attacked and being the attacker.
Zimmerman was talking to police for a couple of minutes and hung up with them. That piece of garbage Martin was hiding between the houses waiting on Zimmerman. When Zimmerman walked by him, Martin attacked.
Zimmerman suffered several injuries including a back injury, two black eyes, a broken nose, and lacerations to the back of the head. Martin on the other hand sustained not even a superficial wound. This according to the autopsy report.
As a CCW holder in my state, I can tell you that in most places, the laws are pretty uniform. In our state (and Florida) the law reads
"A licensed firearm carrier can use deadly force if they believe that they (or others) are in jeopardy of serious bodily harm or death."
Given the multiple injuries Zimmerman suffered, it's more than clear he had every reason to believe he was in jeopardy of just that: serious bodily harm or death. That's why he's a free man. I would have shot Martin too and I probably wouldn't have even been changed unless my attacker was black and it drew national attention.