I mean a .45 would do it. Bigger caliber, bigger assurance. But yeah I don't recommend doing it in front of others, especially this method.
Who's to say you won't drive someone else to suicide by witnessing this though. It's not pretty seeing someone's head blown out/off. In my opinion that wouldn't be fair to possible said person.
Oh and a lot of people like the term FMJ (full metal jacket) thinking that's best in general, but you'd want a hollow point so on initial contact you get that punch from it mushrooming... just saying, an FMJ would more so go in and go out cleanly, therefore survival would increase.