A local gunshop owner went to Africa a year or two ago after buff and took his 375HH with 270gr Winchester failsafe factory fodder. He showed me two recovered bullets from his buff. In both cases the petals had parted company leaving the base to penetrate through the front shoulder and stopped short just under the skin on the other side. I Guess you could expect the Barnes X to give similar results.
Hey "Top Predator" I really appreciate the reloading offer. It would be good to catch up with someone who's been chasing buffalo. I've been talking with Peter Larson of Remote Adventures regarding hunting the wild bulls. Haven't finalised a date yet but apparently Christmas is good with the Bulls in Rutting season. I'll drop you an email when I have a free moment.