I would go with a 225 gr. Barnes X, Nosler Partition, Swift A-Frame, Trophy Bonded Bear Claw, Win. Fail Safe.

My cousin has killed 5 oryx dropping them on the spot using a 225 Barnes X with his 338 Win. Mag.; all were one shot kills right through both shoulders. The furthest shot was at 300 yds. I loaded them using a Max. load of 78.grs. of RL-22 Vel: 2900 f/s. Good luck.