40nm is a lot. I always tighten lock rings, until they start to "stutter." Don't crossthread it, and do grease it, and you really can't overtighten it.
You can leave it too loose, which is not a good thing.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.