"Proper grip for shooting an autoloading pistol" is a subjective term, and I don't think there is any such thing as THE proper grip that's universal, anymore than the "proper shooting position".
When the bullet hits where you want it to go, you don't get points off because you didn't have the "proper" grip.
Guitar players want to argue that concept all the time - "your thumb MUST be here". Whenever someone gets religous about that, I suggest they go to YouTube and watch some videos of guitar players who don't have thumbs.
As long as your fingers and other body parts aren't in a spot where they'll get injured, and you're killing the bullseye, git 'er done.