I noticed for example a 357 mag 125 JFP on speer.com needs 7.5 gr of Universal powder for a starting charge 1148 FPS. But on hodgdon.com a 125 cast LRNFP only needs 4.8 grain of the same powder 1046. So I guess you cannot use the same data with different bullet types. Is this because the jacketed bullets need more oomf the get them moving in the first place to get them started?