Could you and would you are two very different questions when it comes to suicide.
I could probably kill myself with a gun, although I've got no experience with firearms so I could also fuck it up... but would I? No.
Why would I shoot myself to avoid unnecessary pain, when apparently being shot is very painful?
There's no guarantee that shooting myself would instantly kill me, even if I shot myself in the head, and that gunshot wound would probably lead to a much slower, more painful and unpleasant death than starvation.
No matter how bleak the situation, I wouldn't give up hope for salvation regardless of how unlikely it is, because suicide is a rather rash and permanent decision and if death really is inevitable then I'd like to face and experience what ever is going to kill me, rather than take the cheap way out.