i am working on a project. what i need to know is if the distance from the bottom of the outside case head to the bottom of the inside of the case would be consistent from case to case. i know that the primer pockets can stretch over time, but since this is the thickest area of the case, i don't figure that there is much if any stretching in this area on fired brass. below is a picture of a 223 brass for example. i need to know if i picked up a handful of mixed brass, would there be differences in the distance between the red arrows from case to case, and if so how much would you guess?