Suicide by firearm is more likely to succeed than suicide by other methods (for instance poisoning). Per the American Association of Suicidology, "if a gun is used to attempt suicide, a fatal outcome will result 78% to 90% of the time."[1] Suffocation is also very likely to succeed but poisoning results in death less than 5% of the time and falls about 25% of the time.[2] One can make an impulsive decision to commit suicide with a gun while other methods (for instance hanging) may take considerably more thought and preparation. Suicide by firearm seems to be particularly problematic for youth.

[1] - [http://www.suicidology.org/c/document_library/get_file?folde...]

[2] - http://www.cdc.gov/violenceprevention/suicide/statistics/cas...