I have little experience with the 243 per se, but lots with it's cousin, the 6mm Remington. Anyone who says these are inadequate for deer simply has no idea what they are talking about. A well-placed shot from a 243/6mm is deadly on deer sized game, including Black bears. I have shot about 50 deer with the 6mm [whitetails, muleys & blacktails] and 5 Black bears. Never had to chase any of them any distance. A couple of the bears were good size animals, as were several of the muleys/whitetails. That being said, if a 25, 6.5, 270 or a 7mm make you feel better, then that is fine. For a heavier varminter, the 243/6mm is hard to beat, and knocks coyotes down with authority. a 70 or 75 grain pill from a 6mm is death to larger predators like coyotes or wolves. Regards, Eagleye.