With my Harrell's measure, I use the smaller diameter (of the two available) 8" tube. When I have a charge weight that is going to be a tight fit, I approach the point where powder will start to drop carefully, moving the handle slowly. When I first see powder falling in the clear tube, I reverse the handle slightly, just enough to stop the flow, and then go again. For a 6PPC it will take several of these partial drops to complete the charge. I find that the method of dropping is at least as important as the drop tube, in terms of how low in the neck the charge ends up. In the test that I gave the link to, I used the same case and the same exact powder for each filling. The charge was such that when I did a fast drop with the funnel only, the powder overflowed the case, so I had the case on a piece of paper, so that I could catch all of the overflow. I was able to count the granules that spilled and then return them to the scale pan along with those that were in the case for subsequent drops. The reason that I used a funnel, both with and without a drop tube was so that I could reuse the same powder for each filling of the case, eliminating charge variance that would have occurred if I had thrown charges using a measure.
