It's unlikely you will be wearing body armor if (heaven forbid) you find yourself in this sort of situation.
My plan, and you may appropriate any part of it you think may be of help, is to look for someone wearing an Odamna pin, a Che t-shirt, a union button, or something similar, take cover behind them, and return fire.
It's not a perfect plan and will probably not work at all at Tea Party Rallies. Still, it's a plan.
Crusader