I have also read somewhere where you can use a fired 22mag brass with rim cut off as a sleeve in the chamber to fire a 22rf. I think you can only use it as a single shot because a 22mag rifle won't cycle a 22rf.
Years ago I picked up a single six with only the .22mag cylinder. I shot hundreds of .22lr through it without a problem. Only thing negative that happened is it splits the cases. .22lr isn't reloadable anyways so it was never an issue.