Well, for starters, that 243 load you listed is for 55 gr bullets. Most production guns won't shoot those for a hoopers darn. The twist rate in most production 243's is meant to stabilize 75-100 gr bullets. I tried some of those 55 gr bullets about ten years ago, and it was more of a pattern, not a group.LOL Plus, their are many 22-250 varmint loads out their in the stores right now. Good luck