Technically, gunshot to the head could miss the very small brain, and if it does hit the brain, it's the same as blunt trauma or pithing the brain. It's just less hands on, which many people find preferable.
Of course, it would be preferable that you're not put into jail for firing the weapon too, although 90% of cops showing up for a discharged weapon call would probably applaud you if you explained you were killing a snake. Crazy isn't it?