My brother has a Winchester Model 70 classic lightweight in .223 WSSM, 1-10 barrel. We have been trying to find a powder/bullet combination that shoots well in it and we're having no luck. All cases are being neck sized and preped just like we do all our brass so the prep I don't think is the issue here. Although we have not tried full length resizing??? We have tried Varget, AA2230, IMR 4350 with Hornady A-max and V-max bullets from 52Gr, 55, 60, to 75Gr. The groups are not terrible but 1.5" is probably the best we've got. The gun will shoot factory WW 55Gr. Supreme PSP the best at .5" three shot at 100yds. I wonder if we tried some Sierra bullets without the polymer tip if that might make a difference? Has anyone found a good combination for this round?