Been there, done that, Here's what to do. Take a large target, big enough to place 6 red dots, separate from each other. Take your revolver, mark each cylinder with a silver marking pen ( or similar ). 1-2-3- and so forth. From a sand bag rest, fire 5 rounds ( or whatever floats your boat
) from cylinder number one, then do the same with cylinder number 2 and continue until you have fired a complete cycle. You will then know where each cylinder is shooting. I'm betting that you will have one group about 3 inchs from center. Not really unusual, but not as common today as in the yesteryear's., An old handgun hunter will have each cylinder marked. It is not uncommon to have all 6 groups grouped at different points.