What are my chances of sucess with a double barrel 12 gauge?

[TheLastStraw]

Really just seeking reassurance

I plan on placing it behind my head, pointed at the brainstem and using a string or stick to set off both triggers at once

I am not a big fan of in the mouth, I am afraid of messing up the angle and just shooting through my neck

 

[Nonexistence]

http://lostallhope.com/suicide-methods/firearms