I filled my last antelope tag in South Dakota using my Cooper M52 in .280AI running 140gr TTSX bullets over a charge of 60.0gr of IMR4831. I did not chronograph this koad, but according to the manual should have been in the neighborhood of 3150-3200fps at the muzzle.
Once I finally got a good shot at a buck, the terminal performance was excellent. In fact it made quite a mess, not much meat on an antelope, and since my shot was at only about 200 yards the bullet still had a lot of velocity. Good expansion, lots of internal damage, large exit wound, no recovered bullet. I did not hold for a perfect shot, as I had missed a few opportunities earlier that day not holding high enough so I hedged towards a higher hold on the animal. Shot entered more to the top of the chest and behind the shoulder, hit upper ribs, top of lungs had damage, and the bullet pretty much destroyed a few vertebrae and spinal cord. He had been wounded by another hunter at some point, so I'm glad I was able to help him on his way. If he'd been healthy I never would have gotten a clean shot at him within 500 yards. Once season starts they get educated pretty quickly, and it's very tough to get close. At least for me it is, because I suck at hunting.