If I understand the gunsmith correctly, the problem is not with the slide itself, but another slot on the bottom that is not rotating the barrel far enough, allowing the tab on top to slam into the slot in the slide. I wish I had a cougar here so that I could work the slide and see what he is talking about. I remember seeing a recessed slot in the frame though, I cleaned and lubed it with Break Free.
Correction, I remember seeing the slot in the bottom of the barrel. The tab for that is on the recoil spring assy yes?