Yeah,unfortunately the cost of learning whether a gunsmith deserves a reputation (either good -or- bad) can sometimes be measured in ruined gun parts and emptied wallets.
It is always best to ask as many pertinant specific questions as the consumer might formulate BEFORE allowing even a GOOD gunsmith to turn you into a paying customer.
I have question about your revolver. Did this problem of over-advancing of the cylinder rotation -develope- or is it something that has been evident with this particular gun all along?
If it has always had this/these symptom than I would tend to look at the profile of the hand. The early version of Colts style revolvers have the heighth of the "tooth" area of the hand as the initial period of cylinder rotation followed by the side face of the hand "nudging" the side of the ratchet tooth to complete the rotation of the cylinder so that the bolt will drop into the notch or wide area of the leade and not the uncut area of the cylinder's circumferance.
This is all a bit confusing when trying to understand a description rather than illustrations accompanied by captions.
I have learned about the hand/ratchet/bolt timing aspects of my revolvers from the astoundingly well written/illustrated books by Jerry Kuhnhausen (The Colt Single Action Revolvers- A Shop Manual, Volumes 1&2 ) and can only recommend that title as a study guide for learning the intricasies of the deceptively simple cylinder rotating mechanisms employed in these guns.
At about $40.00 for the volume, it is really quite cheaper than allowing a self-proclaimed "gunsmith" or other "expert" audition your guns to learn thier craft on.
Those types rarely apologize by replacing ruined parts or determining "no charge" when the problem remains or is only partially (or worse) "fixed".