ORIGINAL: Bocajnala
If I were using a .243 I probably wouldnt want to go over 200 yards or so, and It would have to be a good angle.
The .243 was built intentionaly on long range shooting Its just starting to stretch its legs at 200 yds. A bullet expands well between 2000 fps and 2800 fps. the 243 still has roughly 2000 fps at 500 yds. Still plenty for penetration and expansion, but probably way farther than most can shoot.