Even then one has to do it right. One of my relatives who is in the medical field told me not long ago about a ward at her hospital which has among its patients some young people (teenagers) who botched their suicide by gun. Among them is a young man who pointed a shotgun under his chin and succeeded in blowing off his face and blinding himself. Now, he's in that ward, awaiting perhaps decades before he dies. The very thought of having no face and being blind depresses the heck out of me. I suppose that he eventually will go home once his family is taught how to care for him, but still...
So, if you're going to do it, point the gun in the right direction. Under the chin doesn't cut it. I happen to know how it's done but I'm not gonna say.
We had one come into the ICU I used to work in, who had shot himself THREE TIMES with a 30-06. He did not make it, but after "missing" twice due to flinching, he still managed to reposition the weapon and pull the trigger a third time. He lasted most of a day, and then became a donor.
We also had a woman for three weeks before the family let her go moved her to a skilled facility that would take her. She had shot herself in the head with a .38; no exit wound. The slug bounced off the opposite side of her skull, and went through another portion of her brain. She was breathing on her own, not ventilated, so no life support to remove.
Other horror stories over the years involving guns done wrong. No, thank you.