The amount of resizing provided by conventional reloading dies has always been dictated by the manufacturing tolerances (SAAMI specifications) of the brass cartridge case itself. Reloading die manufacturers have been forced to design the neck diameter of their dies small enough to accommodate the thinnest possible brass.
This may be as much as .008" - .010" smaller than the maximum cartridge dimensions typically shown in most reloading manuals.
Since the majority of cases that the reloader is likely to encounter in the field are thicker than the minimum specifications that the dies were designed for, case necks are often resized excessively.
It can be easily demonstrated that excessive resizing of the cartridge case quickly leads to stress distortion and concentricity problems. The new Type S - Bushing Style Dies offer a simple solution to this age old problem.