Firearms are one of the more reliable methods of suicide. As a result, this method is not suitable for a suicidal gesture. Only those 100% certain they want to commit suicide should use this method. Note that the success rate of this method when used to the head is much higher than to other parts of the body.
Despite this, research by Frierson and SB Lippman1 on survivors of attempted firearm suicides in the US suggested that 80% of attempts were not pre-meditated (meaning they were generally done on impulse, rather than having been thought through and planned in advance). A reliable method coupled with not much thought is a scary combination, and one wonders if perhaps many of those using this method might not have gone through with it had they thought about what they were doing for a little longer.
As mentioned in the section Most lethal methods of suicide, studies have shown firearms to be between 73% and 92% effective to achieve a lethal outcome in suicide. However, Stone2 notes from studies on unsuccessful firearm attempts that the chances of a successful outcome are as low as 50% if the firearm is aimed into the abdomen (tummy). Shots to the brain have a much higher fatality rate likely to be nearer 90%, or even higher if a shotgun is used.
RL Frierson and SB Lippman, "Psychiatric Consultation for Patients with self -inflicted Gunshot Wounds" Pschosomatics 31 (winter 1990).
Geo Stone, Suicide and Attempted Suicide, 1999.