Use the 405gr, or 444gr PB. Simple. Those PB's have killed water buffalo, and knocked it down with one shot. All on video.
Oh yeah the Dangerous Game steel tip 530gr PB which were almost $60/15 when they were available. Not the ones you mentioned unless ive missed them.
http://www.huntingnet.com/forum/blac...t-buffalo.html
LOL $4 a bullet