I've only shot one deer with a .243 but it was with Remmy Corelokts. Folded up immediately at about 120 yards. Bang flop. I've only got one with it because I don't own a .243. I shot it while I was holding my cousins rifle, but I wouldn't hesitate to use the .243 for deer, or the Corelokts. It's a good choice.
-Jake