Neck Sizing Cheater Washer
Using a washer allows one to neck size with a full length die. First, the full length die is set to properly full length size, and when one wants to only neck size the neck sizing washer is placed between the press and the die to raise the die the thickness of the washer. This allows the old primer to be pressed out, and only the neck to be sized, and sized consistently without purchasing a separate neck sizing die. The washer does not let the die engage the shoulder or the neck close to the shoulder. The top most part of the neck by the case mouth is re-sized to give the proper tension to hold the bullet. No need to buy a neck sizing die for each caliber. One sizing washer can save you hundreds of dollars.
Has automotive uses as well.. its a really big thick washer