Similar in design concept to Reddings Competition Seating Die, the cartridge case is completely supported and aligned with the sizing bushing before the sizing process begins.
As the sizing process starts, the cartridge case remains supported in the tightly chambered, sliding sleeve as it moves upward while the resizing bushing self-centers on the case neck. The decapping rod is maintained in precise alignment by using the internal parts of the die as a linear support much like that of a firing pin. Meanwhile, the micrometer adjustment of the bushing position delivers precise control to the desired amount of neck length to be sized.
These dies were designed for use by Competition Shooters who have meticulously perared their cartridge cases and do not wish to use a sizing button, however, carbide size button kits are available separately. Bushings and shellholders sold separately
Big Book Catalog, Issue:67, Page:516
Sinclair, Issue:4B, Page:038