Rob, I cannot answer your question directly. However, I will relate the second hand information that I have.

A certain famous personage who has made a lot of cape buffalo videotapes named Mark somethingorother told me the following:

1. A spooked buff shot in the lungs with a 375 will go 1 to 2 miles.

2. A spooked buff shot in the lungs with a 416 will go a mile.

3. A spooked buff shot in the lungs with a 458 will go a half a mile.

4. A gutshot buff shot up the rear end with a 500 as follow up will go less than half a mile because the bullet will penetrate all the way to the lungs.

5. A gutshot buff shot up the rear end with a 600 will go a hundred yards or so. The .600 bullet will stop in the paunch, but the momentum of the bullet seems to exhaust the buffalo, and he will stop after 100 yards or so to stand around and rest.

Consider the source and take it for what it is worth.