Well, I had my fun "making believe".

I swapped the cylinders in it just to see if it would fit and turn - it does-perfectly.
But I would have never fired it because the gun is too rare and valuable to jeopardize.
I do know now what my next project will be.
I know they reproduced the 21 and will look for one of those because I want a "fixed sight" .44 mag and now I know how to do it.

Don't worry guys - that pre-21 is back in the safe in its original configuration sleeping comfortably next to its brother - a pre-24