.260 with 140 gr. factory Corelokt at 150 yards on a cow elk did fine for me several years ago. A few weeks earlier it had knocked a cow caribou kicking at @ 200 yds, and a week after the elk, a wolf at 40. It has nother caribou since at @ 100 yds (Sierra handload) to it's credit, which also didn't go anywhere. I'd not hesitate to use it again on elk or moose, with Saddlesore's caveats. And did carry it for 5 days of moose hunting last fall. The moose failed to cooperate by showing me only sub-legal bulls....
The 6.5 X55 isn't much different in performance -just keep it all in the envelope it's designed for.
