I shot mine there in 2010 at 415 yards with a 180 gr Scirocco from a 300 RUM.

Don't go undergunned. I'd recommend a 7mm or 300 Win Mag as minimum with a good, tough ballistic bullet.

I have killed 9 oryx but in Namibia.
My first three were killed with a .30-06 : one with Sierra Game king 180 gr hand-loaded and the two others with PMP soft point 11.7 g from factory.
The six others were killed with a .338 Winchester magnum and Hornady Interbond 225 gr hand-loaded.

The two calibers did the job but for this strong animal I prefer the .338 Winchester magnum.
Every times I touched the chest they don't ran a lot, the farthest was shot at 415 meters (453 yards) ran 20 meters before to die, and two of them are fell down immediatly. For me it's one of the best plains game calibers.

I just returned from Namibia, killing a total of 12 animals. Here are the only bullets that were "caught", with weight in grains and weight retention %. Setup was 7mmRM, 160 Accubond, 3115fps at the muzzle. Barnes not necessary IMO.

[IMG:left] [/IMG]

Congratulations on hunting with Bob Atwood. He is as much A teacher as A guide, and you will do the tracking and it will be your hunt in more ways than is normal on A guided hunt. I had A lot to learn about an incredible animal, and covered A lot of miles on on foot. Rifle shoud be easy to cary and shoot well with bullets you have confidence in. Enjoy an incredible experiance.