Several people have noted on this forum that when using a lot of powder in a case, so much that it tends toward overflowing the case, using a drop tube allows the powder to settle in the case better.

Recently I was loading some 30-06 loads using 63 grains of IMR 7828. I was weighing each charge, and then dumping the powder from the scale pan into a powder funnel, the funnel held over the mouth of the case. I found that 63 gr. of this powder filled the case to the mouth, so much so that there was no space left. I then remembered the remarks about using a drop tube. I don't have one of those, but I decided to see what would happen if I poured the powder out of the pan slowly, while holding it some distance -- maybe 3 or 4 inches -- above the funnel. When I did that, the same amount of powder did not fill the case up to the case mouth; there was a small distance, maybe 1/8 of an inch, from the top of the powder column to the rim of the case mouth.

I don't know why dropping powder from a distance makes it take up less space in the case, but my guess is that doing so allows the powder grains to arrange themselves more efficiently -- more closely packed together -- so that the same amount of powder makes a shorter powder column.

Pouring the powder into the funnel at an angle so the powder spirals around the funnel also helps.

As a last resort, I vibrate powder in. Put funnel on case, charge into funnel, and touch base of case to tumbler or anything else around that vibrates.

An easier way to vibrate is to simply place the cases, with powder in them, in your loading block and set the loading block on the vibrating object...do 50 at once.

Did the same where I find that the more essential compaction factor is speed (i.e. doing it SLOWLY) and not height.
I made the powder grains land on the wall of the funnel from where they hopped fro and back, ending in the case.
The movement of the kernels reminds me of atoms moving in molecules (though I have not seen them yet).

Vibrating 100% full cases seems a rather spilly method to me...