Even without guns involved, there are many regions with antifascist groups which come and give them a beating (see Patriot Front getting run out of Philadelphia). Collective violent resistance intimidates them. Non-violent tactics are essential, they come first and are more important overall, but violence makes them scare to come outside. Just look at the dissolution of the British Union of Fascists after the '43 Group threw bricks at them enough times for a big example (there are many smaller examples - especially since modern neo-nazis tend to recruit scrawny teens online who can't handle getting beaten up).