That .243 should be OK if it will hold 'em all under an inch at 100yds. Tighter would be better. If it were me, I'd have to go with another scope. If I can't see it, I can't hit it.
I've just recently gone to the 95gn Ballistic Tip in my .243 with 44.0gn of Viht N560/CCI BR2's. Getting sub 1/2" groups at 3114fps. First day out with this load (07Nov09) took a groundhog at 580yds. It works!