In a 1996 study, it was found that 5 of 138 (3.6%) studied gunshot suicides involved two gunshots to the head.
Reliable incapacitation is based on physiological effects (tissue disruption) and can only be achieved by decreasing the functioning capability of the CNS. This can be accomplished by direct disruption of brain tissue or indirectly by cerebral hypoxemia from massive bleeding. Targets of immediate incapacitation are restricted to certain CNS areas and targets of rapid incapacitation include the heart, the (thoracic) aorta and the pulmonary artery. Other major blood vessels and major organs (lungs, kidneys, liver, spleen) constitute targets of delayed incapacitation.
Basically, you can shoot yourself in the head, but either miss your brain (a glancing shot) or damage parts of your brain which involve “delayed incapacitation,” leaving you able to finish the job.
The most famous of these cases was Gary Webb, a journalist who had reported in the mid-90s on a supposed CIA connection to the crack cocaine epidemic in the United States. His reporting was disputed, and came under doubt several years after its publication.
Webb took his own life in 2004, shooting himself in the head twice. The implication is that his death wasn’t really a suicide, but was retribution for his reporting.
The L.A. Times reported on the death:
He put his driver’s license on the bed next to him and placed an old .38-caliber revolver near his right ear. When he pulled the trigger, the bullet sliced down through his face, exiting at his left cheek, a non-fatal wound. He pulled the trigger again. The second shot, coroner’s investigators believe, nicked an artery.
The point: “head” doesn’t necessarily mean “brain.” And people who successfully killed themselves in this way, don’t shoot themselves in the head as much as they shoot themselves in the brain.
Morbid as it is to discuss, if you put a gun “near your right ear,” but point the barrel slightly forward and down, the resulting bullet path will miss your brain entirely. You’ll basically shoot yourself through the face from the backside.
But based on the news report above, it sounds like Webb didn’t even do that. It sounds like he missed his brain twice, but the second shot hit a large blood vessel and he bled out.
(Another conspiracy theory that pops up with this theme is Vince Foster, who was Deputy White House Counsel for the Clinton administration. I’ve occasionally seen this described as Foster being found with “two bullet wounds to the back of the head.” However, his autopsy (PDF) clearly documents that Foster shot himself through the mouth once, and the bullet exited the back of his head. Five separate investigations have confirmed this.)