Clips act like a very thick rim from the standpoint of headspacing, and keeping the cartridges from dropping into the chamber. If 9mm cartridges seem to be chambering in your .357, it is because the taper of the case is wedging in the .357 chamber mouth.
Ruger makes 9mm cylinders for Blackhawks, but the ctge. headspaces on its mouth, and with the ejector rod, extraction is not a problem. There have been some 9mm revolvers, with and without clips, but the idea never really caught on.