I am trying to get back into reloading after a lengthly period of inactivity (15 or so years). I have a Speer #10 and #14 manual and a Sierra 3rd Edition and 5th Edition. I was getting ready to load a bunch of 158 gr. JHP .357 and 240 gr JHP .44 mag rounds when I realized that my old pet load data was off the scale for the new manuals. My old .357 load was 15.5 grains of 2400 and a CCI 550 primer. Now the new Sierra manual says no magnum primer and 15 gr. max and the Speer manual says 14.8 gr. max and no magnum primers. I am getting similar info for the .44 mag loads. Is it safe to use mag primers or my old pet loads? I have 600 rounds of primers for the .44 that will be pretty much useless with this new load data and I have already primed 200 rounds of .357 with mag primers and have another 300 primers I just bought. Now what? Is it safe to load my old pet loads or should I scrap it all and start over from scratch?