FWIW, my son used a 6.5x55 in Zim this summer and made some rather impressive kills. He made one shot kills on Wildebeast(2), one dropped on the spot, the other ran about 200 feet and dropped. He also killed 3 Impala, a Duiker, a Reedbuck, and a Zebra. All were one shot kills except the Zebra, which required a finisher because the first shot was a bit too far back. One of the Impala was shot at 220 paces and the Reedbuck was shot at 270 paces. The load was 140 gr. SAF over RL 22, MV was 2800fps. As many have said, the 6.5x55 seems to kill all out of proportion to what one would expect.

Geronimo