Tend to agree with wheels on this one, 500gr lead pills are the way to go.
Charging brain shots..... This is likely and mostly happens on Elle....
Very few cats and or buff are stopped with charging brain shots, it is mostly a centre of mass kind of deal, this is where the serious knock rifles such as the 458 lott's and up, makes a world of difference.
458 Lott is a very popular choice amongst guides, (I reccomend the caliber allot to young and up and coming professional hunters) for 3 reasons.
*cost of fire arm (a good CZ a ph can pick up for $2000 in Africa)
*cost of amunition (in SA around $200 + a box)
* the young guys often find themselves cutting some teeth in SA and quite a number of them go into Moz, Tanzania and other countries, and the possibility does exist that you might not be able to find Lott amunition, in such a case one can always revert to traditional 458 win mag ammo,
Long and short of it you still have a functional fire arm, stranger things have happened.
My best always.