Well, for one thing, nobody ever said for sure that they will EVER come back together. Chances are they will not. Second thing, if you are reloading starting at max charge and decreasing by .5 gr., you are doing things backwards, and may be inviting serious trouble. Better read a loading manual, and pay attention. Also, I don't see any advantage to switching from H4831 to IMR 4831. You need to try a totally different powder. Check your loading manual for an alternative type.