Gun v fist
In US self defense law, there's no expectation that you can't defend yourself with deadly force or a firearm even if you've defending yourself from a beating using fists and kicks. There are places in the world where there's a requirement of proportionality, but not in most American States. You can fire on someone who's coming at you with their fists. You don't need to put down your firearm if it's fisticuffs and get into your boxing stance. You can use a gun to stop yourself from getting beat up.