Three shot groups are a starting point only. If it still held true after at least five five shot groups of each I’d start believing.
When I start working up loads, I load in 5 load batches. But when I shoot and get a poor SD/ES I stop shooting that Load (If the SDs are bad even if I only shoot 2 and the velocity is way apart I stop) and clean and start the next load.J E Custom -- how many shots do you like to use when you're getting a measure of SD?
It only takes 2 to tell you that a load is not working
J E CUSTOM