Bart and others, I usually shoot a 10 shot spread between 1/2 grain powder increments. I take time using rest. But, what is more disturbing is the whole center of group may shift between range visits. And, our range tempature has only differed by 15 pr so degrees. I try my very best when wouking up loads wit this rifle to make sure wind is in face or back. So far I have narrowed it to maybe older leupold. I will post.