So you're agreeing with me? I said it's not a bullet failure if the bullet doesn't exit. Kinda confused about ur post honestly
That depends on the bullet, what it hit, at what angle and how it was designed.
Lot's of variables there. If I put a 375 Solid into the shoulders of Wildebeest, or Buffalo up close and it doesn't exit, I know something is wrong. It didn't track straight through as designed.
If it turns 90 degrees instead of tracking straight through, I know the bullet failed to perform as designed even though it was used exactly as intended.
Now if I put that same bullet through an Oryx and that Oryx runs a couple of miles before cratering, I know it also performed exactly as intended even though the Oryx did not die quickly.
Conversely if I shoot a Hornady Amax out of my 300Rum and it blows up on impact horribly wounding the animal, that's my fault for using a target bullet in a hunting application.
When I see a bonded bullet flatten out the size of a quarter or half dollar on impact with bone and turn 90degrees or more I know the bullet failed to perform as designed.
If I hit a deer with a Nosler Partition in the ribs and close range I know that bullet will pencil straight through and I'm probably going to have to anchor it with another shot or do some tracking.
If that bullet however blows up shallow when it hits the humerus or scapula, I know it failed to perform as intended.
No shooter, rifle, caliber, cartridge, or bullet is perfect and none of them are designed to work right in every imaginable circumstance.
We improve our odds greatly by using the bullet as it's designed and pick our POI accordingly and hit it, but every once in a rare while, they just don't do what they are supposed to do.