Penn, SD is a measurment of uniformity, I believe concerning velocity, the SD is the number 65% of your shots MV will theoretically fall within, hence the smaller number the better. This doesn't mean to worship SD, just "consider" it. It doesn't mean you will find good groups when you find the lowest SD, wouldn't that be nice tho... If you find good 10 shot groups with a load that has an acceptable ES, say 10-15 fps and SD is real low, say 3-5, chances are the ES is high because of a just a couple of shots at the extreme edge. The higher the number of shots, the more accurate the SD numbers will be. To tell you the truth, I pay less attention to SD and more to ES than anything. If you had an SD of 47, the ES was totally unacceptable in my opinion. On the other hand, if ES was 47 and SD was 7 I'd see why ES was so high. I'd mark the case or two that caused the high ES and repeat the test to see if the played along or were causing the problem, cull them if they were. Even if they fell into the group well at 100-200yds, they're going to kill you with fliers at LR if they cause that high of ES.