I recently starting shooting 20 shot strings to gather info on my loads. I understand all the data but I am not positive what is considered good for SD. I know from stats classes the smaller the SD the better but what is considered good for a 20 shot spread? With FF 243 AI brass a 20 shot string fired over 5 minutes I had an SD of 11.5. Is that decent for FF brass? What would be considered a great SD for 20 shots after FF, but also realistic?