I've killed a couple mule/whitetail deer with the 140's from my Creedmoor. Really comes down to your shooting abilities, and if you can reliably put bullets where you want.
They are match bullets with J4 jackets, meaning they don't take much to start coming unglued.
Here is the exit wound from a neck shot, just in front of the shoulders of a typical north Idaho whitetail.
As you can see, it came apart. The best I could tell, it had begun to rip chunks of bullet out as it was spinningng and tumbling. Destructive? Yes sir! Able to punch heavy shoulders and continue straight? No.
As for your BC question.
Litz has tested published(years ago now) in varmint hunter about various BC's of Nosler bullets. It's not hard to find current tested BC numbers to see for yourself. Generally of the bozos still using one G1 number, on bullets such as these: Nosler lies the most about BC, Hornady lies the most about absolutely everything else. But if you can swallow the notion of a single G1 to start with, you really can't complain about someone "not being close" with their BC number. Use Sierra G1 steps and you'll fly pretty closely.