So many things wrong with this idiotic meme.
First, a lot of those "deaths" were due to famine, not executions. A gun doesn't help if you are starving due to a crop failure.
Second, even if you go with the utter bullshit numbers of 60 million dead in China and 20 million dead in Russia (let's all concede 12 million for Nazi Germany), where do you get the other 168 million from? I'd be kind of interested in the math on that one.
Third, Nazi Germany did not ban guns. The Nazis rolled back the gun restrictions passed by the previous Weimar Republic.
So, um, no, I'm not worried that I'm going to starve during a famine, so that's why I have to tolerate Joker Holmes having an AR-15 and a 100 round magazine, because that would be stupid.