You wouldn’t ever intentionally aim for the gun, you’d aim for the body in every single version of this scenario.
In any scenario using firearms. They’re lethal weapons. there’s no way to make them not lethal. (well. Ignoring things like rubber bullets.).
Missing is too easy, and in any case, the only snipers not trained to shoot center mass are pretty much cops; where the ranges are much shorter, and you’re far more likely to have bystanders being held hostage or at risk if a torso-shot doesn’t immediately drop the subject.
Even then, cops are going to go for center mass if they can. For example, Trump would be dead if the shooter had shot for center mass- assuming he wasn’t shooting for center mass.