I'm sorry but none of that makes sense to me dude, headspace is normally measured in thousandths of an inch, do you mean case head seperation? By measuring C.L. of spent cases you can check brass "stretch" and ordinarily in .308 at .005" over SAAMI is where I
remove a little brass from the neck, get back into spec and continue. Your right that at about 4-5 reloads is when the round might be too long to properly chamber, but that's why I measure and trim.