What he said ,start from the bottom and work up, I too have had no problems as wellYou will probably be able to get back up to the 26 grains but start 10% lower and work up checking for pressure signs. I have used magnum and BR primers with no troubles in my .223 and 6BR. with well over maximum loads.
sometimes different brands, whether it be standerd,Magnum or Benchrest primers can meen the difference from a 1" group to a .25" group, some guns just like different primers in the recipeThe question is, "Why?".