If he was "rational" about this, he wouldn't've shot himself. That's just dumb.
No, its fast and effeicient (if you do it right). I would certainly use a gun, if I decided to kill myself.
It's also quite inconsiderate - you do know that someone has to clean up the mess, right? I suppose you might go out into the woods or something, but then people are going to spend time searching for you as well. Just because you might not want to live doesn't mean you have to be a jerk to the people who have decided to stick around.