I will try to find the original post for this photo that has each case identified, the photo was dated the first week of Nov. 2016. It's a mix of factory new, commercial converted, converted by me and fire formed. You can see how much variation there is.
The quality of the die in combination with the hardness of the brass and forming process will determine the quality of the shoulder. Forster and Redding probably have the best off the shelf dies, unless you step up to a Wilson or Whidden.
Remington double strikes their brass and that also helps.
It will get better after it is fired once.