Do you really think everybody else gets similar results, with every powder out there?
Run the math on your own setup, and argue with that.
Fill your hopper, throw about 50 charges, weigh each, and take the standard deviation. Excel or a calculator will do the math. If your SD is greater than about .1 grain for old style 4831, stop and get yourself a decent measure.
Go to a credible web site like Hodgdon, and find the increase in MV per grain of powder. The formula is (max charge MV - start charge MV)/(max charge weight - min charge weight).
Multiply that result times the SD of your powder measure.
Then add that to your background variation by the sum of squares method shown.
If your background variation is about as assumed, your answer will surely be similar. If you're otherwise getting very small MV SDs, then your answer will be different.
Come back and give us your test results.
