Shooting to the temple damages the frontal lobe, both hemispheres with the right caliber, while shooting in your mouth with a 15° angle towards your brain damages your medulla oblongata and high spine. In the first case, you can die, but also end up with permanent damage and survive: phineas gage got a whole iron rod impaled in his left frontal lobe and kept living for more than 10 years. In the second case, over 90% of the cases are deadly: it doesn't matter if you damage your medulla oblongata, which controls many vital functions like breathing and heart rate, or your high spine, which have the same effect of hanging yourself; even if you survive, you'll endure substantial damage to most of your brain areas and massive bleeding, the bullet may ricochet around inside the cranium too. Now, I'm not talking about using an high caliber shotgun, which would just crack your skull open and reduce your brain to mush, but low caliber ones that can be obtained more easily. Shooting in your mouth is much, MUCH more likely to kill you than shooting to the temple.
