The 357Mag barrel has a 1:18¾" twist rate and works fine in other .35 Cal chamberings as long as the bullet isn't too long, I have a 35 Rem Handi that was rechambered from a 357Max, it shoots 240gr cast bullets great to 100yds, haven't shot it past that yet, but 200gr round nose bullets in a 358Win or 35Whelen should work great, I've shot 250gr spitzers into less that an inch at 100yds with my 1:16" RMEF 35 Whelen, whether they would still be stabilized at 300yds I dunno, maybe someday I find out!!
There have been several discussion about rechambering the 357Mag to 358Win or Whelen, use the search feature to find them.
Tim