Back in the day, the 243 was quite popular among elk hunters in my area, northern Wyoming. I knew lots of guys that killed elk with it every year, usually with factory 100 gr. bullets of various makes, and some of them absolutely swore by it. 'Course, every now and then one would get away, but they usually just put that down to bad luck or not holding their tongue just right when they pulled the trigger or some such nonsense. I never thought much of the practice and never used one for big critters myself, but my point is that the 243 can and has taken some very big animals, even though it probably isn't good practice.

The 243 isn't quite as popular now for really big game, most folks having seen the light or died off. The 25-06 is better for bigger animals, but I don't think either of them is really quite enough. I'd say you're better sticking to deer and antelope, and there isn't much difference between them for that purpose in my opinion.