Understood Kyrie.
Just doing our best to provide meaningful guidance, and the 10 - 14% addition is generally accepted.

An explanation of the crusher technique is about 2/3 way down here
https://docs.google.com/document/d/1F2sQuPm05IE4VWYYnCkvuXmYEzQoWd_SQgaAfUOZEFU/edit

Major Sir Gerald Burrard published an estimated Lead Crusher (LUP) (Long) Tons/ Sq. Inch (TSI) to piezoelectric transducer Pounds/ Sq. Inch (PSI) conversion formula in the Third edition of The Modern Shotgun, 1955, Vol. 2 derived from simultaneous crusher and transducer pressure readings in a test barrel.
(Cp x 1.5) - .5 = TSI
TSI X 2240 = PSI

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