You are correct that the FX120 is a major upgrade compared to any scale with a 0.1 gn resolution. I have a V1 Autotrickler system, and i love it! Will probably at some point upgrade to the V3.
Even though superb, the FX120 does not always deliver 0.02 accuracy over 100 rounds, as it can occasionally drift. This is fairly rare, but it can happen if ambient conditions change. You have to preheat the scale for at least 15 minutes before use or there will be substantial drift. I just keep it on for days at a time.
Also, you can load very good ammo with 0.04 gn resolution, because other factors like neck tension differences, bullet and primer weight variations and progressive barrel fouling dominate once you load to two kernel accuracy. In my experience, 2 kernel accuracy is the point of diminishing returns.
My FX120 scale runs on a high end power filter/surge suppressor, and is sitting on an anti-static mat which is properly earthed to avoid static buildup, no fluorescent lights anywhere.
A stray kernel can accidentally get onto your scale tray and go unnoticed for a while. You really have to keep an eye on the negative number every time you remove the pan. Train yourself to look at it before you dump the powder into the case. Once or twice in a loading session you will see that “something” has happened.
Have run the experiment where i loaded 50 rounds as best i can, tweezer in hand, then carefully put bullets upside down in each case to prevent spillage, waited a few hours, and then weighed them all a second time, being super careful. ES was 0.06 gn (2-3 kernel accuracy) and SD was 0.016 gn. Good but not perfect. [Btw: This testing method is flawed: Ideally we should use a Sartorius GD503 or equivalent scale that has 0.001 gn resolution. Since i don’t own one me did the best me could.]
Yes - by all means get one, it is superb, just learn how to use it well: It is sensitive to drafts, so turn off the AC and close the door. I cut a small rectangular hole in the bottom of the front screen and made it slightly larger than the pan, and cut a round hole in the side screen for the trickler spout. Note: If you remove one of the screens, your measurement error will double to 0.07 gn or more. If you use it with no screens, accuracy is less than 0.1 gn and you have wasted your money. If you don’t believe me, try it both ways.
Also: It needs to be mounted on a stable flat surface, and no milligram scale likes vibration, like a truck passing in the street, or the user bumping the table. A granite slab helps. Just mark the position of the feet on the mat and mark the position of the mat on the table so you can pick up if anything got bumped or moved, and recalibrate the scale.
My SDs came down from 12 fps to 6-9 fps range when switching from a 0.1 scale to a 0.02 scale. But understand that in reality it is closer to a 0.05 gn scale. And neck tension differences have a bigger impact than 2 kernels of powder. [Buying a scale capable of 0.001 gn (1/10’th of a kernel of powder) is overkill IMHO (unless you plan to split kernels with a carpet knife???), but if budget is no constraint, go for it. If you are in the BR game and weight sort your primers, you will appreciate the extra resolution.
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Good luck!