Stan,
Now that you know 4 grains of bullseye is too small a load, I think you can increase the second fireforming load to 6 or more grains. Craig's suggestion to load a starting load of shot after the initial forming is worth a try. The case walls not being straight would not prevent using shot as it might prevent seating a bullet. You might have to use a toilet paper wad as an overshot load, though. This could reduce the number of loads needed to blow the cases out.
Mike