Just to test this scale I took a bullet I cast and it weigh 413.5 and then I re-weigh it 413.6 I kept re-weighing and it would be 413.5 two times and then 413.3 then 413.7 ???? Is this normal ? Oh by the way this is in heated room with no draft, no floresent light,no cell phone on a rock solid bench. Thanks.

Digital scales are usually advertised to weigh +-.0l.
When you're weighing 400+ grains, wouldn't sweat the .01 or .02 difference.

Any styrofoam plastic nearby? Some Winchester ammo boxes use it and it will drive a scale nuts, especially if the humidity is low. Other plastics aren't as bad, but you can try moving plastic objects around the bench while you watch the beam.

Bye
Jack

Had a RCBS funnel near and moved it around scale did not change. I took a 20gr check weight a it weigh 19.9 then I pushed the reset button and put the check back on it ,20.0 did 3x still 20.0 , go figure ?

Digital scales are a little sensitive to location of the load on the pan. Be sure to center an object on the pan, or, for powder, shake the pan a little to spread the powder evenly across the whole pan.

The disc under the pan has a little peg that goes thru a guide hole, and contacts the weighing element. If the load is off-center, the peg can hang up a little bit, and cause variation like you're seeing.

Edit: Mine is a PACT, sold under the RCBS label.

Digital scales are usually advertised to weigh +-.0l.
When you're weighing 400+ grains, wouldn't sweat the .01 or .02 difference.

Working in grams will confuse the natives. ;)

I like Jack's suggestion that you have an electrostatic induction problem. If you are running the scale on an adapter, let it warm up 20 minutes. As an experiment, take an aluminum or stainless canning pot or stock pot, and set the scale into that and run a ground wire to a water pipe or outlet ground from the edge of it. This will be awkward to use, but if it makes the variation go away, then you have either a static problem (which this is shielding) or a draft problem (which this is blocking). Try wafting your hand over the scale and see if the reading shifts?

It is completely normal for the least significant digit (LSD) of a digital scale to jump up and down one count. If the scale electronics are sophisticated, this will happen only when the actual measurement lands right in between two successive LSD values. Such electronics average many readings before updating the display. Less sophisticated measuring electronics will run plus or minus one LSB.

A well designed digital scale will be immune to the load location on the pan, but simpler ones will not. Look for one with a four-point load cell pan coupling. The CED Pocket Scale and the old Dillon Terminator scale (I don't know about the current crop) have this load position immune system. So will a lab scale like the Acculab VIC-123 (Sinclair has these for powder measuring).

Load cells made from plastic will exhibit some hysteresis that metal load cells won't. Taking a long time to return to zero after removing a larger weight is a sign of this situation. Just note how long the return to zero takes after using the check weight, then don't measure any more frequently than that, even at loads too small to see the hysteresis lag. Re-zeroing just before every measurement is a common lab practice that minimizes error.

Thanks for the replys guys, I am going to try centering the bullet and see. I called Lyman and talked to a very polite lady, but you know it was like going to some gun shops and asking qustions.