Metal plates are not only a lot more inconvenient to carry but also means that you're within inhabited space where you can simply buy a lot of bullets from nearby merchants, which downplays its crafting value since you can't craft it "on the field" like you would with repair kits and such. Additionally the metal quality doesn't matter.
Therefore crafting bullets should use metal scraps for 1-2 scraps per bullet, as metal scraps are far lighter compared to metal plates (and thus far easier to carry) and do not have quality.
