Really? I could swear the running news said he was out of ammo and unable to follow his plan of using the last on himself?
That he didn’t use it on himself seems to me to make the case that he is sane.
Here is a link that says he had 900 rounds.
http://www.norwaynews.com/en/~view.php?72T9454PI54827A285Lgg844RJ2887R776Gym353J8Q8