Not surprisingly the .243 has a strong following. It doesn't kick much although, like a .22-250, it can bark pretty good, particularly from a short barrel. Rifles chambered for it tend to be accurate, that was certainly the case with my SAKO Varmint when I owned one years ago and the Remington/Lilja M-7 I own now. In those jurisdictions that have a minimum bore diameter for big game, the .243 is probably legal, although it's advantage over a .22-250 is debatable.
On game up to 100 pounds the .243 when mated with an appropriate bullet produces sufficient penetration and kills well, but IMHO the idea that the .243 makes an ideal general purpose big game cartridge overstates it's effectiveness. In the North it shines as a wolf/caribou gun, but wolves generally fall into the 100 pound range and caribou are perhaps the easiest of any big game to kill, and tend to be taken broadside. In the southern US where whitetail weight tends to be closer to 100 pounds the varmint to deer monicker is more appropriate than on the Canadian prairies. As a general purpose big game cartridge, the .243 does not meet the requirement of having a reasonable expectation of killing any big game animal with a single shot, from any direction or angle, within the range limitations of the rifle, cartridge, and hunter. There is not enough mass in a .243 bullet to ensure sufficient penetration at close range and as it's velocity bleeds off with range, this does not bode well for long range lethality despite its flat trajectory. Either the 6.5X55 or the 7X57 are better big game cartridges, and both exhibit the mild manners necessary for the recoil shy rifleman to optimize his marksmanship skills, and both have better bullet mass to velocity ratios to ensure deep penetration on large game.
On these pages we occasionally see the .243 touted for bear, moose and elk. While it can and has been used with some success at the large end of the North American big game spectrum, in those cases the .243 should be reserved as the expert's choice, and in many cases an expert would rather have something larger. When he's armed with a .243, the expert knows not to try a quartering shot, neither front or rear, he knows to keep away from large bones, and he knows to work the action at the shoulder for a fast follow up shot should he need one. If you have to wait for the animal to provide you with a text book broadside shot, you need more gun.
