30-06 does the job nicely, 458 does too.
They are evil looking and to watch them feeding is eye opener, they will rip, chew, snarl bare teeth and really go for it, with each other too, I wouldn`t like to meet one on a dark night.
Hell of a set of jaws/teeth on them,powerful too.
Some people say they are hard to kill, I haven`t found so, just stick the bullet in the right place.