I guess I am lucky due to FL law does have a castle clause. And it not only pertains to your home, business, but also to your car and any where you happen to be.
So we have law on our side to defend ourselves from bodily harm without penalty.
Now with that said, if you are on the phone with 911 remember, it is being recorded and can and will be used against you in court if the BG or their family sues you. As you all can think up recent examples of this I am sure.
So, being on the phone with 911 I would most certainly yell, GTFO , STOP, then followed by bang x15 (9mm, 14 for my 40) followed by reloading. Well, maybe not the whole mag but at least "enough to stop the threat."