I have one electronic, three beam scales, including an RCBS, a Lyman, and a Lee. All four weigh differently, as much as a half grain. I have weights to calibrate, and when calibrated, they will still vary.
I just picked the Lyman, and work up slowly. So my 19 gr. may be 19.5, but if it shoots well and no pressure, its all good.
The electronic scale seems as repeatable as the beams to me.
Ben