Altho Case Head expansion (CHE) has been considered the best approach to measure excessive pressure - The physicist/statistician Denton Branwell has demonstrated that CHE cannot be used to measure over pressure. ( Even with my exceptional Mitutoyo .0001 blade Mike ) On my RUM brass, the primer pocket radius grows about 3x as much as the Case Head - so primer pocket radius is a more sensitive indicator. (it's probably also more uniform) Suppose I take my preped (uniform the primer radius) brass and have a machinist make me some <font color="brown">go, go with force /ubbthreads/images/graemlins/cool.gif , no-go gauges </font> to slip into the primer pocket. I would have a fast way to measure primer pocket expansion. I would like to use this approach in conjunction with the RSI rsi pressure trace system. (also using factory ammo as a reality check). When I get a Allen uber Mag, I won't have the luxury of factory ammo. comments, suggestions, idea please.