Are you saving your brass? If not did you look at it? You could have had a piece come into and you have the shoulder and neck still in the barrel. Also get hold of the barrel with one hand and action with the other and try to unscrew the barrel. Any give would show the possibility of barrel movement causing headspace to change. The other most likely thing is ammo just a bit out of spec for the chamber which seems unlikely since the headspace gauge did work and now does not.
Bookmarks