Is the 45 AutoRim like the 45 ACP, but with the rim so you don’t need the half-moon clips?
That's the feller. Or, with the half-moon [or full-moon] clips, you can load and unload all the chambers of the cylinder in one move, nearly as fast as a magazine change for a semiauto. Alternately, a speedloader can be used, though they're bulkier.