I just saw this post. The .243 WSSM is what I use for antelope and I also use the 95 Ballistic Silvertips.

This is 2007 result.

One Shot DONE!

To give you an idea I am 6'1" and about 270 so the horns are a little bigger then they appear with me in the picture. 16 1/2" to tip and about 2" spades.