Anybody have any data using MagPro or IMR4831? I've been working with RL22 but would like to try some others. Working with 100gr Partitions and 110 Accubonds mainly.

Thanks!

*I* started with 270WSM loads, backed down 10%... which, btw, is easier to form brass from for a 257JLS.

So, a 130 or 140gr 270WSM load would ROUGHLY equate to a 100 or 110gr 25WSM load (minus 10% for starting loads). I was kinda thinking along that line but wasn't sure. This is my first wildcat and I'm probably being overly cautious but I'd rather not blow anything up! Then again, I don't want to get a load that is too low. That can cause it's own problems from what I've read... Thanks for the input!

For a .300 WSM necked down to .25 caliber, I would think Magpro might even be a little fast. Maybe you should consider Reloder 25, H-1000 or Vihtavuori N-170. While you could load IMR-4831, my bet is it wouldn't give you top velocity. I would probably look up .257 Weatherby loads, reduce by 10% and carefully work up.