I have seen the same thing twice IF that what 's TOM is describing--but both times with 150-grain cup-and-core bullets, one on a mule deer buck that weighed, field-dressed, 232 pounds after a week of hanging in my garage, the other on an average 6x6 elk elk shot just under the chin as it stood looking at the hunter (not me) at less than 100 yards in lodgepole timber.
The elk was only found after half a mile of tracking a very thin blood trail in snow. The bullet, luckily, had partially clipped one of the major blood vessels, so eventually keeled over. The shot on the mule deer was a "finisher" after it had been shot frontally in the center of the chest at 20-25 yards, also in timber. The first bullet exited through the spine at the rear of the ribcage (the buck was standing above me on a moderate slope), but the second was found, minus the core, resting gently against the spine.
As many have pointed out, bullet penetration matters more than cartridge, bullet weight, etc.
Oh I realise it could happen but unless the deer is killed and a post mortem performed, you can never be sure just what exactly went wrong.
