Actually, the subtract from zero will need to take place whether a cartridge is used on the scale or not.I like your idea about the weighing of the cartridge and loading the powder directly into it from the dispenser. I dont know if it is too difficult to make it an option, so you could do both methods, with and without the cartridge. If it is too hard or time consuming, then just forget about it, its just an idea.
Simply dispensing powder onto an empty scale would not be a good idea; the powder would scatter everywhere - ball would be the worst, but most of what both of us deal with is extruded cylindrical powders, which would also scatter in all directions.
Flake powder might stay on the scale, but one wouldn't want to sneeze....
In any event, a container needs to be used to hold the charge, more or less centered on the scale for best accuracy. The container will have some weight, even if it is made from aluminum foil or paper. The weight of the container must be accounted for, whether it is as simple as a muffin tin, a piece of formed aluminum foil, a paper or cardboard cup, a cartridge, or whatever - the weight of the container must be subtracted from the weight of the powder charge.
From the powders you posted, it looks like most of what you are reloading for are high-powered rifles in the range of 6.5mm to perhaps 8mm.
What are the particular cartridges you are loading for, the approximate weight of empty but primed cartridges, and the approximate range of powder weights that you are using?
Please do not post your particular loads; just a simple summary is all I am asking for.
I reload in many calibers, from .380 Auto (pistol) to .30-06; powder weights from 2gr to 58gr using flake powder for light loads and cylindrical powder for high-power loads. I think that most of your loads will fall into the latter category.
I've made some corrections in your spelling that I have italicized. One of the most difficult parts of the English language is that very similar-sounding words can be used properly or improperly. "To", "Too" and "Two" are three words that are very confusing, even to those who speak the language.
"Two" - a noun; a name; refers to the number 2
"To" - a preposition; as in "I will go to the store"
"Too" - an adverb; as in "It was too high a mountain to climb"