As this question is posed in the Antelope forum, I won't mention ground squirrels or elk. As with any big game animal, the first 4 out of 5 important things in killing an antelope is bullet placement with the fifth maybe being bullet type. Stay away from frangible varmint bullets and hit them in the chest & you've got meat on the table. A poorly hit antelope is as tough as any animal out there and if someone tells you that "all I've gotta do is touch one with this magic magnum super slayer bullet" realize real quick that that someone doesn't know a thing about antelope!
That being said, I've shot or seen them shot with .223's to 45-70's and with standard bullets (cor-lokts & silvertips) to high end premium bullets. The only bullet I didn't care for was the Hornady Interlok, in this case an '06 165 gr more because of the damage it caused than because of any lack of killing power. The meat is too tastey to waste and a bullet designed for penetration (partition, Barnes X, A-frame, etc.) seems to kill as well without the destruction of meat. Too, if I could only use a cor-lokt bullet in any reasonable antelope caliber & if it was accurate in the chosen gun, I wouldn't loose any sleep over it.