What would be the real consequences for punching a neo nazi in the USA?

If it were still the Wild West, I could duke it out with subscribers to this growing fascist trend and let chips fall where they may. However, they can act tough, be offensive and instigate, and then call it assault if someone even yells at them, leaving me screwed with criminal or civil charges. Could someone with legal knowledge spell out a worst case and best case scenario? If I walked up and cold cocked one of these pricks vs started a verbal altercation and let it escalate to taking a hit and defending myself aggressively would be other variables to consider. I believe in law and order down to my core, but it’s come to this here. And “never don’t punch a nazi.” Thank you.