I don't know if this is a bug or something else but I think it is important to share it : when we acquire Null Composure a first time from Banshee-44, the Gunsmith, we own it with the curated roll. But, when you want to buy it in the collections, you can buy it but it is not under his curated roll form, and it is not possible to upgrade it like any weapon in the game. You can apply a mod but this is impossible to apply the range masterwork. If somebody as an answer, I take it.