Standard deviation is the average of all readings calculated. Chronograph 5-20 shots and calculate the average for your dope chart. Extreme spread is the difference from lowest to highest chrono reading. When I reload I try to stay under 20 FPS ES or I keep tweaking the load till I reach that.So I got that ES is difference from slowest to fastest...... Is sd the average of the difference of speed from shot to shot then? Math is ot my Forte..... Thanks
Or a mathematician. Smells better coming out of the chrono.So sd is a number your chrono ***** out then?