"freebore" is usally set at@..625 thou. that is, the bullet never toches the rifiling untill it is free of the case. "Leade", on the other hand, can be set long. for heavy bullets, or short, for light bullets. In other words, if you have a long leade, short bullets may not ever touch the rifiling, while seated in the case. With a short leade, or throat, a heavy bullet may need to be seated deeper in the case. Also, the bullet ojive differs from style of bullet( round nose to spitzer) or even just different weights of the same brand of bullets. Respectfully Terry