Which S Class heroes can be hurt by firearms? In Episode 123 of the manga is revealed,


   Pig god can't be hurt by firearms


We know other S Class heroes can't be hurt by firearms, such as Zombie man. But we see an S class rival as Garou in his first stage, someone who is capable to defeat the weakest S class heroes, having to divert a large amount of bullets from a gatling gun and having his hands bleeding from that. Is it known which S Class heroes can't be hurt by firearms, and if there is any who can be damaged by them?
The one hero that comes to mind is King. As mentioned here, King is actually weak. He has no special abilities whatsoever, aside from being a video game expert. 

It is no overstatement to say that he is the weakest among all the heroes in the Hero Association. He's just a normal person and like any normal person, getting shot by firearms would severely hurt or incapacitate him, depending on the type or where he would be hit.