Daryl, I think your right about a bad primer being the problem as the load of 125grs brings the powder level to within 1/4" of the base of the bullet. Enough that I wouldn't need a Dacron filler. What puzzles me is that I can't imagine a flame that would clump the powder and turn it yellow as if it started to burn and not completely ignite it. It had to be a partial burn to push the bullet into the barrel.