Actually, it is if you hit the brain stem directly. There hasn't been any stories of people hitting the brainstem, whether with a heavy or light caliber and survived or lived to tell about it. The people who failed via firearms are those who hit some other non-lethal part of the brain/body and were likely saved before they succumbed to death (either via bloodloss, trauma, or shock). The people who survived gunshot wounds oftenly aimed below the chin (which is a very, very bad idea and Hollywood movies are BS when it comes to reality, especially firearm suicides) and/or hit the frontal lobe of their brain (blowing out their reasoning, logic, and speech area of the brain, whereas life sustaining parts of the brain, the brainstem and the back of the brain are those that control bloodflow, heart, and breathing.)