Bellm requires only running the .444 Marlin case into a FL .308 Win. However, when starting with new bulk .444 brass, sort out cases with significant dents and distortions at the case mouth, since these will often propagate into creases in the neck which will split.
Boxed brass is generally better.
If the necks are not dented, once fired .444s form with virtually no losses. Losses from new bulk brass should not exceed 6-8 per 100. 7mm Bellm requires at least necking down in a .308 Win. die first, and then running into a 7mm-08 die. The size die is correctly adjusted when a formed and trimmed case will drop into the chamber with the barrel OFF the frame, and the case head will be either perfectly flush with the end of the barrel or protrude no more than the thickness of a sheet of paper. Or, ignore this warning, do it your way, and learn the hard way like I did.