What Caliber to use to hunt Crocodiles?!?

G'day mate,if your in Australia you cant shoot crocodiles they are protected,but if you need to protect yr self you can shoot it but you cant take the skin because if you do they will charge you for shooting a protected species.But if i came across one i would be using a 308 cal because i would be hunting wild pig in the areas where the croc's would be .cheers mate