Same thing happened to me about 23 years ago with a NEW Colt SAA. The only thing it was soaking in was Hoppe's #9. It didn't get down to dull grey, just mottled, dim coloring.

I think the problem was the soak went over the intended time and lasted for 3 days.

Have you actually used all those ingredients for a e day soak of S x S's before and had no adverse effects?

This is one for the books. Tough way to get in the books, but that's life.