Stan;
Tell me in Layman's terms why, IF, a lead crusher is calibrated to give a certain reduction in length at say 8K psi & it is then fired in a test barrel fitted with both crusher & Piezzo Electric readings at the same distance from the breech the crusher gage will not be reduced to that same extent & thus read a lower pressure.

Think this over carefully & take your time. After your answer, we will go from there. I am not trying to introduce any "Flat Earth" HooDoo but sound mathematical principles.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra