That's a hard one because every rifle is unique unto itself. I have one bolt action that shoots anything I've thrown at it with sub MOA groups. Those same shells in other rifles will sometimes group reasonable well but not to those rifles best accuracy potential. Started loading for the 223 in 1974 with WW748 powder. Moved to H335 and H322 later settling on H335. Recently tried VV N130 and VV N133 but wasn't impressed with the results. Have tried Varget, Benchmark, Reloader 10, AA2520, AA2230 and BL-C(2). H335 is still my favorate most versitle powder in this caliber. I couldn't get the 40 grain bullets to group well from 1-9 twist barrels. They worked very good on 50 and 55 grain bullets. Any of the reloading manuals for various powders I've listed have starting and maximum loads. My best most accurate loads were far from the published maximums in those manuals.