What do you define as "long range?" 400? 600? 1000? The .243 can theoretically reach out to 1000 if loaded hot however there are better choices. 400-600 you could do ok.
I can pretty easily put all shots from my Savage .243 into a 3 inch group on the head of a silhouette target at 450 yds with my handloads. I use 6.5 grendel for 500-1000 and .338 at 800-1400. I just shoot long range for fun though, I don't actually compete with these so I don't know what kind of rules or restrictions you face.