The point is, you're not helping him. He has no confidence in the bullet now and by you telling him joe blow had perfect sucess with that load and bullet you're thinking he'll just forget his experience. All you're trying to do is defend the powerbelt. Let it go and help him find something else he's confident in. If he comes back next week and says 'hey shot a deer w/a Barnes or Nosler and got the same result' then we know there's something up.
Wise words - confidence is IMPORTANT!!!! He wants to try something else - telling him to just forget it and keep trying is not help.
BTW, I've killed many deer that had fistfulls of hair on the ground and made perfect lung shots on them. It doesn't mean for sure that it was a bad hit. If it was white belly hair, then yeah I'll give you that.
My experiance as well.