African Hunter,
Your results with the 600 are what I have come to expect out of a 404 or 416, not that much different IMO..Same for Saeeds 375-404 Wildcat...

I have shot a few Buffalo with the 505 Gibbs, .470 and lesser calibers and seen them shot with the 500 N.E., 500 Jefferys and 577 and all got about the same results as far as I could tell..about like yours..

Apparantly this incenses some folks, but it is what I have seen over the years, like it or not...Buffalo and elephant just succomb so fast from shoulder shots, they run a bit and then die except for the ocassional instant kill and some folks sure put a lot of measure on one instant kill, I do not, I just mark those down to fate...The only instant kill I ever got on a shoulder shot Buffalo was with a 370 gr. Northfork out of a 416 Rem at 225 yards, probably a sliver of bullet cut the spine or whatever...

Most bulls shot properly in the shoulders will run 40 yards to a half mile shot with anything, sometime further, but if they are misshot, damn near nothing will stop them after they get pumped with adrenaline except a brain or spine shot and ocassionally a good heart shot will instantly kill a charging bull. I have been told it is when the bullet explodes the heart the instant the front feet hit the ground on a running bull..I think this is correct as Doctari said this, and a couple of vet friends of mine said it was so, and I bow to their profession...