Shot mine this year with a .257 Wby Mag that I bought and setup specifically for hunting antelope, wearing a 6-24x50 scope with a mil dot reticle. Setup worked perfectly, although the scope is on the heavy side.

Any cartridge .243 up should work. I agree with the comments about the wind. It seems like it is always blowing out on the plains. Check state regs for minimum caliber requirements.