About how long will surgery take for a self inflicted gun shot to the head?

My friend tried to commit suicide about two hours ago, and so far there hasn't been any news. I'm just worried and would like a time frame of how long the surgery might last. So far the silver lining is that he's in the 1/3rd of people with cranial bullet wounds that survive the trip to the hospital. Would anyone happen to know what his chances of survival might be too? I'm really worried. Serious answers only please. :(