You didn't ask about correlation. Any two sets of data can be correlated, but that doesn’t mean that one can be converted to the other, nor does it mean that the correlation is evidence of a cause-and-effect relationship.

For example, I can (and have) correlated rainfall and water temperature in Chesapeake Bay, Virginia. There is a significant inverse relationship. Rain usually, but not always, depresses water temperature in the Bay. In this example there is a cause-and-effect relationship, but it is not perfect, nor is it consistent.

Landings of the Pacific fish anchoveta (in Chile) correlate significantly with the wholesale price of menhaden in Virginia. There is no cause-and-effect relationship. Rather, a third factor (ENSO) jointly influences both.

Certainly, one would expect that higher pressure would result in greater deformation of a copper crusher slug. There will be a significant correlation between the two. That does not mean that one can be reliably converted to the other. It is for this reason that SAAMI now supplies both CUP and PSI standards for the cartridges it oversees.