I'm in the process of working up a load for the rifle shown in the thread here and was discussing drop tubes with a coworker because I'm working with compressed loads. The general thought is that a long drop tube allows a few more grains of powder in the case before the load is compressed. In addition, the more ordered packing of kernels can lower ES and SD numbers which can often be correlated to smaller groups at long range. I ordered a couple of drop tubes from Midway and borrowed my coworker's drop tube last night to run a very small test. Both cases shown in the photo below are new .308 Win Lapua and both are shown with 50.8gr of Varget. The case on the left was filled using a .30 cal Satern funnel whereas the case on the right was filled using an MTM funnel with a 4" drop tube. Clearly the case on the right has kernels more densely packed so what's the physics here? Any thoughts?
http://www.midwayusa.com/product/613906/mtm-universal-powder-funnel-set-17-to-45-caliber
http://www.midwayusa.com/product/293879/forster-blue-ribbon-powder-funnel-with-long-drop-tube
http://www.midwayusa.com/product/613906/mtm-universal-powder-funnel-set-17-to-45-caliber
http://www.midwayusa.com/product/293879/forster-blue-ribbon-powder-funnel-with-long-drop-tube