Headspace is not related to the case. Its the distance between the bolt face and the shoulder datum point when the bolt is completely closed. We size the brass to fit the chamber to that particular dimension. The dimension varies from rifle to rifle.
The headspace on any caliber is set by...
You stated: "Slack or improper alignment Is not conducive to consistency, so it should be minimized. One of the quickest ways to spot poor workmanship, is to try a fired case in an action/chamber for ease of closing. Many times it will have to be index't in the same position it was fired in to...