For the mathematically inclined ...
If you have a "micrometer" adjust powder measure and a fancy calculator or software on your computer that does statistics, linear regression in particular, you can get set so you don't have to use a scale much at all after doing the initial work. What follows works best for loaders who buy large quantities of single powder lot numbers.
Here's what we do with a Redding BR-30 for a new lot of powder. Set the adjustment to 20. Not 20 grains, just the 20 mark on the dial. Fill the hopper with powder and throw some charges to stabilize the powder column. Now throw five charges and weigh them together. Divide by five. Record this average weight.
Adjust the dial to 25. Throw some stabilizing charges, returning them to the hopper. Throw five charges and weigh together. Divide by five. Record the average weight.
Adjust the dial to 30. Throw some stabilizing charges, returning them to the hopper. Throw five charges and weigh together. Divide by five. Record the average weight.
.
.
.
Adjust the dial to 75. Throw some stabilizing charges, returning them to the hopper. Throw five charges and weigh together. Divide by five. Record the average weight.
So now we have a collection of ordered pairs, each a match between a dial setting and a powder weight. If the powder measure is a good one and our throwing technique checks out, we can plot these ordered pairs on an x-y coordinate system and they should lie very nearly on a line. Here's where the calculator/computer comes in.
Enter the data into a stat package and do a linear regression. The result will be a function relating dial setting to powder weight for that lot of powder. Record this on a reference sheet taped to the powder jug.
I've done this for many jugs of powder, and using the weight-dial function works very well for quickly getting a powder measure adjusted to new charge weights. Of course, once pet loads are established, their measure settings go on a cheat sheet taped on the wall near the powder measure.
I did something similar, but much less thorough. I simply recorded the micrometer setting for a given charge with a given powder, then when I want to load some more of a previously recorded powder/charge combo, I just dial in to the pre-recorded setting, double check the charge on my scale and move forward.
Your knowledge and system is admittedly much more impressive though.
