jorge,
The tendency of A-Frames to not exit buffalo is one reason some PH's like them. As I mentioned in an earlier post, several PH's I know prefer the 270 TSX .375 to the 300 TSX, because it has less tendency to exit buffalo, thus preventing the exiting bullet from hitting another buffalo in a herd. This happens occasionally, a decidedly stressful complication! A-Frames tend to expand widely, the reason they don't usually exit, but it's also why they put a big hole in whatever they hit, an excellent combination.
What loads have you tried with the 300-grain Partition? It's shot well for me in three .375's, two H&H's and a Ruger, especially in the Mark X Mauser I've had for over 25 years now. Though it doesn't shoot any better than the 270-grain TSX, which will probably be the bullet used if I ever go on another buffalo hunt.
