I wouldn't call The Gunfight at the O.K. Corral a "B" Western, what with Kirk Douglas and Burt Lancaster and all.
Depends on your definition of what a "B" movie is today. The movie of which you speak has an all star cast, to be sure. But when I see it on TNT as part of a "marathon," it takes on the vestiges of the genre. How does Gunfight at the OK Corral stack up against Open Range? In comparison to that (lots of contemporary star power there, too) the older movie looks like a cartoon in terms of even just the dialog.