Jumping off your reply to Roses and snipping your post for emphasis, MassGuy.
What if this is all intentional because it's what he wants LE/everyone to believe?
Buys a gun that morning (This was a rash decision and no planning went into it.) - Instead, could have very well been planning for a while.
Tells someone he's going to kill himself after killing a lot of people. (Don't look too intently for me. My body will probably never be found anyway.) Diversion as he makes his way to planned location to wait for LE to assume his body is in the woods somewhere.
Runs into the woods abandoning vehicle. (I have no means to go very far.) - Knew that vehicle would be of no use as soon as bolo was out. Could have planned other means to flee area if not hiding out deep in the woods with stashed essentials.
Abandoning rifle and ammunition. (I'll be unarmed.) - Seems likely he has another as one was said to be used during previous run in with neighbor.
MOO