Actually, if one looks at gatherings of NRA members, it is hard to see any difference at all from a Neo-Nazi or Klan rally.   And that is because they are generally the same people: they are all 100% white.   

It would be difficult to find a more racist organization than the NRA.   So if you want to compare people to Nazi leaders, you should look to men like Wayne Robert LaPierre, Jr. as appropriate examples of the same mindset at work.    He even physically resembles Adolph Hitler.

So don't compare sane progressives who support gun control to Joseph Goebbels.   That dog won't hunt, as the racist white southern boys often say.