My cousin has madeone shot kills on 5 oryx with this load:

Cartridge: .338 Win. Mag.
Case: Winchester
Primer Fed. 215
Bullet: Barnes 225 gr. XFB
Powder: RL-22 MIN: 73.0 grs. VEL: 2782 f/s; MAX: 78.0 grs. VEL: 2919 f/s.

DON'T FORGET TO START AT MIN!!

Good luck.