I cannot think of much better a cartridge for light plains game than the 250 Sav. I assume your rifle is a modern one, but old 99's had a 14" twist and a lot of modern strong bullets won't stabilize..........these include bullets clear down to the 85 grain Nosler black tip, and most anything bigger than 100grains. New 10' twist guns no problem with anything. I own three 250's currently. I use a 100 grain Sierra Pro Hunter and 4320 powder.......two grains more in the bolt. I have killed animals weighing over 1000 pounds (yes) with this cartridge, but red Hartebeeste would be a better upper limit, and Red Leg is right...I found velocity alone was not the answer................I have always wanted to take a 250 to Africa. Be sure to let us know how things go...................FW Bill