I don't use the adjustable bar on my Auto Disks but mine varied about + /- 0.3 grain when I experimented with using up some old Unique that was given to me.
That was a little more than I was willing to accept even running mid range loads.
My Auto Disks only varies 0.1 grain with AA#5, 231, Red Dot, or Bullseye. I just stick to running these powders in them and don't experiment with Unique anymore.
The FA digital scale is also very sensitive to battery voltage. Mine needs a new battery every few months or so at the rate I use it. It took me a hot min to figure out why my Auto Disk powder charges were all of a sudden +/-0.3 (I was using 231 on 45ACP), when for months since I bought that FA scale (and checked it for accuracy) they were throwing perfect.... drug out my old Lee Saftey Scale (LOL) and threw 10 charges in a row that were perfect.... Installed new battery in the FA digital scale and it was back to reading perfect on every throw....
Will