Moe was based on the real-life Bugsy Siegel, who was an ally of Meyer Lansky and, through Lansky, Charlie Luciano. But he was an independent operator in LA and Vegas. The real-life Siegel pushed around LA's two top Italian mobsters: Tony (the Admiral) Cornero and Jack Dragna, though I don't believe he slapped them around in public. That was probably a factor (but not the biggest factor) in his own assassination.