I am jumping into this post a little late it seems, but I will post none-the-less.
I have a REM 700 that was a .284WIN that is away getting a new barrel for it, a 6.5/284. The idea behind it is to be able to really reach out and touch pigs over the floodplains (and get back into the fly shoot at the range). I had thought that if a buffalo presented itself would I shoot it with this cartridge? I don't think that I would as I could not guarantee it would be mortally wounded if a typical shot was made on the chest or shoulders. However, a shot placed to the neck or spine would certainly do the job and allow a finisher if required. Even though this rifle will (hopefully) be a less than 0.5 MOA rifle, would you trust it enough over 400+ meters to hit a large live target well? Pigs will be no probs but a buff? I don't know...

Anybody have experiences with spine shooting a buffalo?