Accuracy in counter-balance scales

[Vitnir]

Has anyone thought about how accurate scales are in general? Since manufactures in general don't label their scales with it's inherit inaccuracy I'm left guessing when I want to buy a scale to measure gun powder. Most counter-weight scales I have seen gives on the read out for instance 4.3 grains (280 mg) which would imply a accuracy at +/- 0.05 grains which would seem like too good to be true. Comments?

[Soapy Sam]

If it's a straightforward balance you have, then one way to check for internal error is to swap a pair of weights from one pan to the other. If the scale is level in both cases, then there is no bias to one pan or the other. That's relative accuracy.
Whether you have absolute accuracy depends on your calibration weights. I know zilch about ballistics, but I would expect U.S. calibration weights will be closely monitored for accuracy. (Do they have a U.L or U.S. Gov. mark?). To check them, you might try your local High School or college. Ask a chemistry teacher if you can check some loads on his lab scales. This is practical chemistry and physics in the field, after all. He may be able to make a lesson of it.

If you are loading your own, I suppose the true test is to keep very accurate notes, then get your local gun club to let you do some range testing with the gun fixed in position to eliminate variation due to kick etc. (Is this apt to damage a gun? I don't know). I assume there are tables of expected range for a given load weight/ projectile weight combination. (This assumes identical quality control in the propellant composition, but there's not much you can do about that except buy from reputable suppliers). Better done on an indoor range to avoid wind effects etc.

Probably the best person to ask would be the range master there. (Pardon my ignorance of the vocabulary. I never fired a gun in my life. I do know several Americans and Germans who hunt and load their own shells and they all seem to be pretty pernickity about getting this sort of thing exactly right, for good reasons.)

This all sounds like an excellent college project.:)