Powder can certainly be weighed but I guess mycomment is why would you want to?

Usually the main attractionof getting into muzzleloading is to learnand master the shooting & hunting tachniques used with muzzleloaders the way our ancesters did back in the early American traditional muzzleloading era.
(however, somedon't, preferring instead to use modern high pereformance scoped inlinesjust to take advantage of the specialhunting seasons established by/for the traditional muzzleloader hunters)

Real blackpowder's whole history is based upon using "volumetric" charges...weighing powder charges would not be somethng the typical settler would have done...doubt theycould have even if they'd wanted to given the lack of precision scales, etc...and lastly,there's really no measureable benefit to doing it....