I am working up my loads and my velocity is moving between 10 fps to 70 fps. What is an acceptable range between rounds? The powder is the same weight, bullets weigh the same, primers are the same, ammo temp is the same, cases are the same length, trimmed to length each time. Not sure what is going on, unless the norma cases are different thickness, but they are all out of the same lot. I have not weighed them yet. Any ideas?