I have a few 250-3000s, all pre 1920, and when I get above 87gr they don't shoot well. I know this isn't uncommon, but do the newer pre-mils handle the heavier bullets better?
All premils had the same 1-14" twist rate. Maybe they got better later on with always hitting that 1-14" twist and had fewer slow twists, but they'll all have problems with longer 100gr bullets.