The purpose of the scale weight set is to check the scale, but more importantly to check yourself; it is not hard to set a scale incorrectly (i.e., 75.0 grains instead of 70.5 grains of powder). It may be an uncommon occurrence, but if you have a bad mistake only one time is enough. I see it is as a three way check system; I zero the scale, then set the charge, then double check with the weights, then weigh the charge on the scale. A tip I learned here on the Campfire is to wipe off the blade, knife edges, and stones occasionally with rubbing alcohol if your balance scale seems to be acting erratically.
