?? I never had such an issue with .300's. In my experience they behave just like any other .30 cartridge when seating bullets. Have you checked the diameter of your expander ball?
I have to have an expander ball first before I can measure it. I bought an RCBS two-die set. Resize/deprime and a bullet seating/crimp die thus the neck expansion die purchase (that flares the cartridge ever so little to accept a jacketed bullet)
I bought an RCBS two-die set. Resize/deprime and a bullet seating/crimp die thus the neck expansion die purchase (that flares the cartridge ever so little to accept a jacketed bullet)