For the record, a western must take place in the Americas or it's not a western IMO.
So while A New Hope is the only Star Wars movie I like, and part of that is because it very much uses the archetypes of westerns, I would not consider it western enough to be a western. Whereas Django includes a battle between the old frontier and the new frontier not necessarily in the "old west", but in old west times and includes every other aspect of a western film in the process. So it meets enough of the criteria.