Hi,
The prepared case activates the dropper tube. If your powder drop is adjusted for a longer case, a shorter case will obviously receive a shallower depth of expansion
and less flare compared to a longer case. Being shorter, it will naturally lift the dropper tube less than a longer case does. If your dropper is adjusted for a longer case, a
short case may not even lift the dropper tube high enough to allow the ball bearings to exit the dropper bore - no bullet will drop.
I suggest sampling your brass and determining the shortest cases you're likely to use and set the powder drop and bullet dropper to operate with that case length.
Longer cases will then be expanded a bit more deeply and perhaps have more flare than needed, but the shorter cases will at least activate the dropper.
Then, to correctly set the dropper, unscrew it a few turns upward and position a prepared (short) case under the dropper. Operate the press handle down and leave it there.
With the dropper full of bullets, screw it downward. when it contacts the case, the dropper tube will stop moving downward, but the die body will continue
threading into the toolhead. Note the point at which you see the column of bullets drop and then screw the die down 1/4 turn or so deeper, to give a little over-travel.
That's all you need. Hand tighten the lock nut and you're good to go (not with a wrench or you may crack the relatively thin-walled aluminum die).
When the dropper is properly adjusted, once the bullet column has fallen, and the bottom bullet is on the case mouth, screwing the die down farther doesn't do anything.
The column has fallen and can't fall any farther. As an analogy, It's like when you squeeze the trigger... once the hammer falls, continuing to squeeze the trigger harder won't do
anything. The hammer has already fallen.
Rick (a.k.a. Mr.Bulletfeeder)