.338 Win Mag is the primary rifle I always take to Africa. It’s fantastic for just about everything except dangerous game that requires .375 or bigger, though I would not hesitate to shoot a Buffalo with it. I shoot 225 grain Barnes TTSX Bullets and have had great results on everything I’ve ever shot with that bullet.
That‘s interesting ammo, but it’s very old. I’d shoot some of it over a chronograph before I’d hunt with it. I’m guessing it’s over 30 years old based on the boxes.
Ammunition is about the least expensive part of an African hunt, so why don’t you just buy some new Barnes TTSX if you can find them, or perhaps Trophy Bonded Bearclaws or Nosler Partitions in a Federal loading. You can’t go wrong with any of those.
I just got back from Tanzania a couple weeks ago, shot Lichtenstein Hartebeest, bushbuck, sable and Zebra with my .338. Animals ranged from bang-flop to going perhaps 100 yards, all 1-shot kills.