Dre,
I have used 250 and 286-grain Barnes Xs in my 9.3x62, both the grooveless "pre-TSX" and TSX, and they work. But in my experience they do not kill as quickly as lead-cores at the moderate velocities of the 9.3x62, and the deep penetration result in problems when hunting buffalo in herds, due to exiting more often. In fact, I know more than one African PH who recommends TSXs in the .375 H&H for buffalo--but advises using the 270-grain (or even the 250-grain TTSX) instead of the 300-grain, because the 270 is less likely to exit when hunting buffalo in herds, possibly wounding another buffalo. My preference would be for the 250-grain TTSX, since it can be driven faster, and in my experience more velocity results in quicker kills with monolithic bullets of any brand. But even with 250s the 9.3x62 isn't a speed demon. About 2650-2700 fps is top end.
Also, the 9.3x62 doesn't have as much powder room as the .375 H&H, and loading the very long 286 TSXs can be a problem, even with very dense Big Game powder. I was able to use Big Game with the original 286-grain X-Bullet, but the powder charge was heavily compressed. The 286 TSX is a little longer, and didn't want to stay in place over Big Game.
