Some confusion here between accuracy and precision. As a reloader, one doesn't need a high degree of accuracy. You do want a high level of precision. Accuracy refers to being correct. Example: If a specific bullet weighs a known 70.0000 grains, and on your balance (it's not a scale--a scale is for linear measurement) measures the weight of that bullet at 70.2 grains, it's accuracy is off by .2 grains (at that weight). Weighing your powder within an accuracy range of even a grain is not important. Don't go ballistic now--read on. What is important is precision, which is repeatability. Example: If we take that same bullet and weigh it 5 times and it always reads 70.2 grains, you have precision. If it weighs 70.3, then 70.1, then 70.4, then 70.2, then 70.1, you don't have good precision. It doesn't really matter if you know exactly what your powder charge weighs, i.e. accuracy (within limits), but it is important that the weight reading is always the same, i.e. precision. You want the same charge each time (precision), but the fact that a different balance might give a different weight reading for that charge (accuracy) doesn't matter. It won't effect you (your loads). Poor precision will effect your loads.
So, don't worry about chasing accuracy, especially since, unless they are very expensive, your check weights doubtfully are very accurate themselves, and certainly using a bullet as a check weight does not provide an accurate measurement. Evaluate the precision of your balance by measuring the reading of a single object several times over. To really evaluate precision, you need to do this at several different weights. It is common for a balance to be accurate in a relatively small range, but precise over a much larger range. Hope this helps.
