ldholton,
Measuring CHE doesn't work UNLESS you have a pressure-tested load to compare it to, using exactly the same brass. I've run several experiments on this in a commercial piezo-electronic lab, and brass varies so much in thickness and the exact composition that anybody who claims X amount of expansion means Y PSI doesn't know what they're talking about, much less whether the load is "safe."
A chronograph is a far better indicator than CHE.
