It is basically what I do, I also make a point like "your being awfully hateful, were you this hateful when different racists were burning cities?" or "If you think someone who disagrees with you should be shot, you may want to consider there is more wrong with you than there is them". 9 times out of 10 that shuts them up. Doesn't matter that I have in the past said we should round up all the socialists and shoot them, they don't know that and even if they did pointing it out just makes them have to acknowledge they are basically doing the same thing a "right wing terrorist" is doing. Best is when I got one to apologize profusely when I told them as a jewish person them saying that conservatives nowadays are literal nazis was incredibly insulting and demeaned the sacrifice of all the millions of jews that died in the holocaust lol.