RE: .308 or .243
Depends on what type of factory load though. If you are talking 80 grn it could either be a big game bullet or a varmint bullet. They are very different in how they react to game. A big game bullet is designed to have controlled expansion giving it better penetration and retaining bullet weight. A varmint bullet is designed to expand rapidly and fragment for less penetration and dumping more energy into the animal.
And normally the faster the bullet the more they tend to expand, so an 80 grn is pretty light for a deer in my personal opinion. Not that it wouldn't work if it was properly constructed. And some times bullets do freak things. You can't base bullet performance off from one incident, it would take shooting many animals to gain a true understanding of what it will really do reliably.
Paul