Did you have any florescent lights around and on the same electrical circuit and did you have a Ferrite on the power feed to "Choke" out frequency signals.I've been chasing flyer problems with my rifle. When I finally took my Gempro 250 to my dads to check it against his tuned O'haus beam scale I found the Gempro to be all over the place. To the point it was dangerous. Maybe mine was a fluke but I wouldn't give $5 for another one. I'll never trust it
You also should have the scale - as all- Electonic scales powered on for at least one hour before use (We do 24 hours).
We used the Gem Pro 250 and it was very ACCURATE.