Lyman called for a filler (probably dacron) for some of their 45-70 loads in one of their older manuals. I loaded my .45-70 ammo. with the filler per the data. Then, for no reason I know of, they dropped the filler from the data. I have to believe there was a problem with the filler, although I never experienced it. I stopped using the filler. It is no doubt rare that a problem would occur but it only has to happen once to ruin your whole day!