Make a dipper.
Drop a charge into a case. I usually insert a spent primer in the primer pocket backwards to close the flash hole.
Mark the level on the side of the case. Cut the case off at or a little above the line. Super glue a handle of some sort into the rim. Use a file to trim dipper to get correct charge weigh.
Bingo. Problem solved.
I have and use a bunch of these. They're very repeatable and handy to use.
And they're CHEAP.
All the Best,
10th Amendment -
The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.