LOL! So, that means he's entitled to a free punch, regardless of how many teeth end up missing, or whether her head splits open when it hits the floor?
Not at all, but the response must be reasonable and proportionate. A bullet for a punch is neither reasonable nor proportionate in most circumstances or in most states. A punch for a punch... or even swinging a barstool or beerstein in response to a punch... is far more likely to be seen as proportional and reasonable. Even in extremely gun-friendly states, there are virtually zero instances where a court considered gunfire as an appropriate response to fists.