About this 'gun'.
To even force yourself into believing Travis had a gun is almost an impossible feat. Why didn't anyone know about this gun? Not even his roommates (who were in potential danger with a firearm in the house) knew. Nor his best friend, Chris. And Jodi even admitted Travis didn't own a gun. The fact that she re-invented it speaks for itself.
No one is likely to keep a gun for protection (because it wasn't for fun or for hunting seeing he couldn't carry it anywhere without a permit WHICH...he didn't have) and keep it far from reach on top of some closet.
What purpose is it serving up there? That's like buying a spare tire then...leaving it in your garage. Placing it somewhere where it's not useful is fruitless. Unless of course we're to believe Travis expected to catch burglars in his closet one day!! The whole gun-the-closet theory is ridiculous.