personally I cannot stand the standard Lee Mandrel's I think that they are too big.... I have sanded down all my standard Mandrell's another 1.5 thousands of an inch or I have ordered them direct from Lee. I know get what I definitely think is the proper tension without having to crank the heck out of my handle on my press... and beat up the sleeve on the die. When I set up the die I only measure on the inside of the case mouth and neck I never worry about the outside dimension... and often there is a ridge near the case mouth that is not removed by outside deburring which can throw your Dimensions off an easy .001 to .002 in.
