Remember, b-c gap is measured with the cylinder held to the rear; check on each charge hole and from both sides of the gap...This is all great information. Thanks everyone! Waiting in anticipation for the feeler gauges to be delivered tomorrow.
...after you have checked, double-checked and triple-checked, then checked again, that the revolver is unloaded and safe to work on.
Depending on your measurements, if you're in spec and the revolver functions correctly under fire without spitting or shaving, I'm squarely in the camp of leaving it alone.
If you have an extraordinary gap or develop issues shooting, there are plenty of options and we can walk you through them, but basically it's about getting to a qualified revolversmith.
Long as you have the feeler gauges, check your endshake and headspace, too.