I've hunted more with the 9,3x62 than any other cartridge and have had excellent results with 250gr. TSX and 286gr. NP. I've never slayed a cape buff, but wouldn't hesitate using either bullet.
Personally, my rifle loves the 286gr. NP so I've settled on.
Close to 20 years ago, not long after Barnes and Nosler started making 9.3mm bullets, I attended a hunt/event at a Texas ranch, which included my friend Richard Mann's demonstration of a new kind of bullet-test media he'd developed, using wax which retained the shape of the bullet channel. Among other bullets, we planned to test some of the 250 and 286 Barnes X's, and the 286 Partitions.
I bet Richard that the 286 Partition would penetrate somewhere between the 250 and 286 Xs, due to being a "partition forward" design. He looked doubtful, but wouldn't put money on it. But that's exactly what happened....
