Why do people put pistols in their mouth to kill themselves?

I’m remembering a scene from Fight Club and Possessor where the main characters put pistols in their mouth in an attempt to “kill themselves” (plus other movies I’ve seen).

In Fight Club, Tyler misses (I guess on purpose), and in Possessor, the main character needs to do it after completing a contract (to leave the body she possessed).

In Possessor, the angle suggests she might miss her brain entirely.

I can understand something like a shotgun; it’s not exactly something you can hold to your temple, but why put a pistol in your mouth?

Is it more effective somehow? Does it hit a part of your brain where firing from the side might otherwise leave you alive, yet disabled?

I’m sure you could argue it’s just more dramatic from a movie critic perspective, but I’m sure people have really done this, and it maybe be a case of art imitating life, but I believe it would be the other way around.