There are a couple reasons I do not like or recommend cream of wheat or any other filler type fire forming. One is simple, walnut shells can be used as a sand blasting media, think about that. Second is how we are forming the case and how the forming differs. When you fire form with a bullet and powder you essentially have a pressure vessel with pressure forcing the case outwards in all directions. This why cases shorten up when formed, they are pulling brass down into the shoulder. This is the correct way to do it IMO. With cow you are compressing a media under high pressure and then forcing it through the neck, pulling the neck forward stretching the shoulder brass. What I want to see in a formed case is 2 things. I want the case to shorten, and I want the oal variation to remain the same as virgin cases or close to it. If new brass has a .003" variation short to long, I want to see .003" variation after ffing as well. If you end up with .010" variation for example, you have not formed cases in a consistent way.