Neck tension on Short Action Custom Dies

2-3 thou under the diameter of a loaded round.

Get 0.006

Then make it 0.004 or 0.002 with mandrels.

6 won't work brass or stretch necks much.

Use their calculator on the page for the die. I use the one sided brass measurement and I use their carbide decapping expanding mandrel. The calculator tells you which bushing and which size mandrel. This has resulted in very consistent necks for interference fits/friction.

I like their dies. I have seen a few instances of the shoulder bump being inconsistent, almost certainly the result of too much lube on the cases. So watch out for that.