I used to fireforme cases using the filler method but I found the case mouths often came out very crooked and needed lots of trimming as well as uneven neck thickness. I also had some case head separation with that method, mabye I wasn't doing it right. I tried expanding the necks and fireforming with a bullet loaded into the lands to control the headspace. What I liked the best was expanding the necks a little over sized, then sizing back down and creating a false shoulder to headspace on.
