The Forster Bushing Full Length Sizing Die offers advanced precision by allowing you to precisely control the amount of neck sizing tension in your reloaded brass while sizing the body and bumping the shoulder. This die improves accuracy and prolongs case life because the case's shoulder and body is sized down just enough to fit in a minimum-sized SAAMI rifle chamber and bushing limits working of the neck. 

The bushing resizes the case neck just enough to grip the new bullet. But not enough to over-work the brass. One of the three bushings included will accomplish this. So you'll get more reloads before your brass gives out.