John, I've probably had close to 20 sets of Talleys and never, ever had an issue or crack. I suspect something else was at work with that rifle's receiver (if we're talking about the same Kimber 7-08).
He also had an all-steel base crack too...
“Perfection is Achieved Not When There Is Nothing More to Add, But When There Is Nothing Left to Take Away” Antoine de Saint-Exupery