My guess is they were or really soft. I mentioned he should have a smith take a look at the indexing, possibly polish/bevel the forcing cone, etc. if he was going to shoot cast exclusively.
Was a S&W 686. Never had that experience before or since.
I have one in 8 3/8” that shoots perfectly.
I have a number of Magna-port guns and always try to go “down to the end” of the firing line away from people to be considerate.
If I ever think about buying a used revolver (or a new one for that matter). I check the end shake with a feeler gauge and I will carry a range rod of that caliber with me and check every indexed position.
There are a lot of other things I check to, but those two are the first.