So I've got this custom 458 that I want to shoot before I decide if I'm going to keep it and buy dies ect... I'm being cheap about this so I've figured out how to size and neck up 338 WM cases I picked up at the range to 458 using dies on hand and a couple of lathe made expanders. In the vein of cheapness I want to use PP bullets, maybe even on deer this year if I get it done soon enough and results are good. I have a bunch of 385 gr RNFP bullets from a Lyman die that was thinking about sizing down to 452, patch, then size to 458. I'd like to run them in the 2000-2200 fps range. Can I use load data for a similar weight jacketed bullet or is it some thing in between jacketed and lead data? I have a pretty good assortment of powders to choose from.