It?s amazing how James can ask such a simple question and have it result in such a loooong thread and passionate exchange. I have stayed on the porch so far on this thread as I am a relative small pup in the field of big dogs that are sharing their experiences and opinions.
Getting back to the original question I would define bullet failure as a projectile that either fragments prematurely without imparting a fatal wound on an animal or a bullet that penetrates without making a sufficient wound channel to quickly kill or immobilize an animal. Penetration is great but obviously controlled expansion will kill quicker if the penetration is adequate. It?s my preference that a bullet creates a larger than caliber would channel and always exits to create the best possible blood trail if the animal does not drop. Additionally, bullet placement and using enough gun are baseline requirements for properly judging a bullets performance. The rules certainly change as the game gets bigger. So another important rule is to properly match the bullet and cartridge to the game.