My son gave me a Frankford Arsenal Universal Bullet Seater. So far I am extremely impressed with it. I started running all the brass through the neck sizer and cleaning the inside of the necks with rubbing alcohol. Loading for 3 different fire arms, there wasn't more than .002" difference...
There are too many variables to the question. Are you annealing the brass? Are you cleaning before sizing? Are you measuring to the tip of the bullet, or ogive? Wet tumbling or dry?
Tumbling or vibratory cleaners will cause the necks of the brass to collide with each other. If you've...