Fx120i scale with the Adam MacDonald v4 AutoTrickler. I previously used the V2 and V3 versions.
First off I’m not sure exactly how accurately I really need to measure my charges, but I usually measure them to +/- 0.02 grains because it feels good, and it’s easy to do with the system I’m using. The biggest reasons to use the system are convenience and speed.
The weight is pretty much never dead on internally, but due to the rounding on the display, it can appear to be dead on to 2 hundredths of a grain, or to a thousandth of a gram. This happens probably 25-50% of the time for me, with the finer-kerneled N130 at the 50% mark, and the coarser-kerneled H4831 and N560 at the 25% range. I usually use +/- 0.02 or +/- 0.03 grains as my tolerance.
Practically speaking, the only two outcomes are the charge weight is within the tolerance, or an overthrow. This is because the trickler doesn’t stop if you are more than tolerance under the target weight.
If the last powder to fall is just a single kernel, then the outcome is almost always somewhere between the target weight or below, but within tolerance. If you are working in grains, the scale rounds the answer to +/- 0.02 grains. This is around 10-40% of the charges thrown, depending on kernel size.
When the trickler drops two kernels instead of one as the last powder before it stops, usually the charge will be over the target weight but within tolerance. I just use that charge and go on to the next one. This is what happens most of the time, but again it depends on kernel size and the tolerance you specify.
With any trickler, you can have 2-3 or more kernels bridge and then all fall at the same time. When the charge thrown is over the tolerance weight by 1-2 kernels, I usually just reach into the cup and remove 1-2 kernels. If it’s off by more than that, I usually just pull the cup and dump 10-20 kernels into the hopper. When the trickler sees that you are now below tolerance it will restart to try again. If I’m loading for practice and I’m expecting high winds, I don’t worry about the charge being 1-2 kernels over weight.
I only have experience with the rod-shaped powders. I’m curious what experiences users have had using ball shaped powders.
There are two practices that help me get better results (more charges that are within tolerance the first time). One is that if I want 39.40 grains as a target, I subtract 0.01 grains from that and I enter 39.39 as my target. Because the outcomes are skewed a little above the target, I just shift the target down a little and then I get an outcome distribution closer to what I want. The other useful practice is that I weigh 10-20 kernels and also count them, and calculate the average weight, only one time per powder. I then ensure that I’m using a tolerance that is bigger than the average weight of 1 kernel. This seems to work out fine because when I’m using finer powder, it’s usually for 30-40 grain charges, but with coarser powder, it’s 50-60 grain charges. The tolerance is relatively the same percentage of the total charge weight.
As for unpleasantness of switching powders, I wouldn’t say it’s too bad. I like the process better with the V4. One very nice enhancement of V4 over previous versions is that the hopper must be closed on the bottom before you can pull it off the unit. Anything that helps me avoid dumping powder on the bench is a welcome improvement. I can’t comment on how difficult it is vs other systems because this scale with the V2 AutoTrickler was my first powder dispensing gear.
