billa, you bring some good experience to the table, well done! Any cup & core bullet can fail if it makes contact right off the muzzle with hard bone, etc at pretty much it's maximum design limits.
But look at all the buffalo Lynn Thompson killed with Hornady bullets when they were off a ways & also remember the 2 amazing Cape Buffalo our new member hammered with Horandy XTP's & the bullets looked amazing, how do we counter that, we can't! Remember, both were off a little ways.
Friend Ken O'Neil had taken some massive Bison & Water Buffalo using Hornady bullets & had no problems & he's done it more than once. This bullet thing doesn't come down to one success or one failure & call it good or bad. Same way with cast, shoot high velocity & hit heavy bone right off the muzzle & the bullet loses, slow things down a tick & you might see a different outcome. Crazy game we play for sure. Don't think there's one right answer for every situation.

Dick