My grandparents both got tags probably ten years ago. They both tagged nice oryx. It is possibly one of the toughest North American animals to kill. They borrowed a friends 7mm RUM (much harder hitting than a .270, of course) and said it was on the very bottom end of knock down they would use again. Of course, even a 223 would kill an elephant, but I would try to use something suited for more tough, hardy game. I would go with a 300 win mag or better.