Coldswede, according to Chuck Hawks the 6.5 x 68 can be loaded with 63.0 Gr. of 4831 pushing a 140 Gr. bullet at 2993 FPS. That is just a little more than 200 FPS that I get out of my Swedish Mauser. Given that I have stated that I would take an "optimal" shot on the kudu of a lifetime if that was the only rifle I had available. The additional 200 FPS might make me breathe a little easier but IMHO it should still be considered a marginal caliber for an animal that can weigh 700 lbs. My son took a Zebra with a 270 unfortunately he had to shoot it several times. I know that there will be those that say they dropped Kudu and Zebra in their tracks using a 270. I also believe that there are many more that chased a wounded animal of that size for a considerable distance before being able to shoot it two or three more times. In short capable yes, preferred or optimal, no. If I knew ahead of time that I was going to be hunting either of these animals, I opt for something with more horsepower. I think my "cut-off" for your 6.5 x 68 would be Gemsbok, Blue/Black Wildebeest, Sable, Waterbuck etc.
