Agree with Head, you need to consider a 75 grain bullet.Typical 223 is 1 in 12. I have a friend that just had a 22-243 built with a 1 in 8 twist. He was determined to try his 55 grains based off his 22-250 load before he had the gun rebuilt. Found out the gun make was right when he recommended the 90 grain bergers. He couldn't come close in his groupings with the lighter bullets to the accuracy he is getting out of the 90 bergers.