I load too many calibers to have a powder assembly for each. I don’t even have tool heads for everything and I have quite a few tool heads. Since it does take some time to set up the press, I just load bigger batches so I don’t need to load that caliber again for quite a while. If I am working up a load and haven’t made the big batch yet, I either leave the press set up with that caliber or leave the powder assembly on the tool head until I am finished. At that point, the powder assembly can go to the next project. The dies will stay in the tool head unless it is needed for something else.
Knobs on the powder measure bolt help quite a bit on adjustments. This looks like a good source:
https://www.ebay.com/itm/Dillon-Pow...925842?hash=item2658d22b12:g:QMoAAOSw2z9gJINM I just ordered several. In the past, I had bought the knobs at Home Depot. They just push onto the hex nut.
Adjusting the powder measure to a new charge is pretty quick. I normally get the thrower within a grain or two after a relatively few number of throws. The powder gets dumped back into the hopper. At that point, I am rotating the knob one or more revolutions at a time. If you are a long way away, weigh a charge and then open the knob two turns and drop another charge. Figure the rough number of grains per turn and then you can figure out approximately how many turns to get to where you are going with the next throw. After just a couple throws, you will be within a grain or two. I make sure that I am throwing lighter charges than I want so that adjusting the charge bar is always opening it and not compressing a charge already in the powder bar.
Once I am close, I charge a case and put it next to my scale. I start throwing real charges into primed brass, weighing every one. The powder in the extra charged case is used to trickle in the amount of powder I need to get to the desired weight. The powder is dumped from the scale back into the case and put back into the press and a bullet is seated. I also adjust (open) the powder bar by 1/4 to 1/2 or so turn and then throw the next charge. I keep repeating the cycle, reducing the amount that the charge bar is changed as I get closer to the final weight. After I get to the final weight, I still weigh the next 5 or so charges to confirm it, I haven’t ever counted, but I probably get a charge dialed in with 10-15 throws. Add another 5 for confirmation, and then start the batch.
I think it’s important to always open the powder bar when adjusting it. If I ever need to close it, I will do it at the top of the press stroke when the powder bar has already dropped its powder so it’s empty. Going one direction also eliminates any backlash in the screw, making the adjustments much easier.