Thanks for posted some very useful informationRCBS, Lyman and Cabelas sell check weights to insure that your scale is reading properly. A much cheaper and simpler way to verify your scale or caliper is reading the correct measurements is to get some new coins from the bank.
The United State Mints are very exact on their weights, thickness and diameters of each coin they produce.
For the scale, the coins weight is measured in grams out to 3 decimal places 1/1000 or .001 grams !! Much better than your scale's accuracy or need for reloading gunpowder. This is better than weighing a 240 grain bullet that can be out of specifications for comparison. If you throw 10 charges of powder and weight it and divide by 10 you will also be able to verify your consistancy using the powder drop as well.
For your caliper, the thickness or diameter for each coin can be measured to be sure your caliper is reading to correct specifications. This will insure that when measuring your rifle cases for length or diameter, they are correct to SAAMI specifications. Meaning they will load and chamber from a magazine properly. If not, then you need to trim to proper length or full length size the case or chuck the cartridge if showing a bulge or head separation issues, etc...
Stay safe and ask questions when in doubt.