Ok. Thank you very much for the info. I was just curious as I thought I had read that somewhere, but obviously I was mistaken AGAIN.I would say perhaps "inspired by" rather than "based off". The Base, Rim and Shoulder diameters are different, so you can't really form a 404 case into either of the Ruger cases.
The same goes for the WS(S)M families of cartridges, the Nosler 26,28 etc. I believe that the only true children of the 404 J are the Dakota proprietary cartridges, and the 400 Tembo.