I think I understand the guages and their headspace measurement along with measuring of fired cases to get an idea of individual chamber headspace. Admittedly my googiefie is suspect, and I haven't spent much time looking, but on the unfired ammo itself, I cannot find "headspace" max/mins. Just distance of shoulder breaks from the base.
Would someone please straighten me out and educate me as to the minimum headspace for unfired 223 and for 556 ammo? Thanks