I also suspect that there isn't as much discussion of .257 handloads because it's been known for a long time that IMR4350 works great with bullets from 100-120 grains--and since H4350 appeared it also proved to work very well.
Plus, there aren't as many handloaders who use it for varmint shooting, despite Ned Roberts' original primary purpose for the cartridge being woodchucks. The 4350s aren't as good for lighter bullets.
