D:

You're right. Scovill had no data from Hornady, and I'm sure that's the source of all the confusion.

Just spoke to one of the engineers on the project. Max pressure for the .375 Ruger is 62,000 PSI - same as the .375 H & H. Hornady specifically wanted it that way. He confirmed that the cartridge is not based on the 8X68S. Base diameter is .532".