Note your chambers then shoot a six shot group loading the same chamber until you have shot all six chambers. Swab the bore after you complete each series from each chamber. Lay down the six targets and compare. There should be something that is distinct.
(1) no chamber can shoot a tight group
(2) certain chambers shoot better than others
Lose the scope and shoot off a rest at 25yds maybe shoot .44 special for the test since the recoil could begin to interfere.
Have a second party do the same thing with your gun. It will take a while but you'll have a good idea whats going on when your finished.
Also and Im sure you checked the sights, (your scope may be damaged so get rid of that variable by testing the gun and not the scope).
One more thing make sure your grips are TIGHT. If they are snug it will cause poor grouping. They must be TIGHT.