I don't know of any reason for it either. I figured they(Hodgdon) would have given up testing in CUP by now and perhaps converted back to be consistent, and was surprised by new data being published in CUP.

A number of years back I wrote a simple application that converted from CUP to PSI. It was loosely based on relational data and was less reliable in the extremes of pressure data. The thought was they may have a more accurate conversion with all the data they possess.

I didn't make my sense to me why someone would believe a simulation over tested data, but there it was. He was obdurate.

There is no accounting for taste.

Experience is a great thing as long as one survives it.

Generally, there ain't a lot that separates the two however,
Barely making it is a whole lot more satisfying than barely not making it.