ou812bob;
Just to expand on Brian's post. He's entirely correct when he said that the folks who have aquired an extra cylinder & just put it in & used it were lucky. If the cylinder isn't properly timed with the pawl & cylinder lock-up, the bore of the cylinder will not be concentric with the barrel. Minor variations can be accomodated by the forcing cone in the barrel, but accuracy will almost certainly suffer. Larger variations will cause lead shaving. It would be extremely unusual, but a gross variation would allow the fired bullet to impact the edge of the barrel to the point that you'd have an adventure you didn't want to have.
900F