As much as I can’t stand Alec he is innocent of any wrongdoing imo. He was not responsible for loading the gun, and I think it’s unreasonable to expect him to unload the gun to check if the ammunition was blanks instead of bullets. Thus I believe a reasonable person would find him innocent of even involuntary manslaughter.

they do not have different laws apply to actors on a set

No but circumstances matter, and as I’ve already stated I believe it is unreasonable to expect him to check the ammunition when the set “expert” was responsible for loading the gun with the proper ammunition.