The slightest change in the air movement can change readings on a digital scale. I use them at work for small plastic parts.Another vote for a balance beam scale for weighing powder charges. The digital scales are handy for weighing brass and bullets but they are prone to drift for a variety of reasons. Gravity is a constant.
1.0 grains is its total accuracy? That's pretty crude. The Lee weighs to 0.05 grains. My RCBS weighs to 0.10 grains. Unless you made a mistake in what you wrote, you need a finer-measuring scale...It can actually [weigh] 1 grain of Varget extruded powder.