Col. Harrumph
Member
Being terrified of double loads and of embarrassing squibs too, my method is to load a bunch at a time (usually 50) and line them up next to each other in the loading block. Then give the block a few taps to settle any "bridged" powder. Hold the lot up to a light source at a slant and compare each case to its neighbors, looking for where the shadow falls on the top of the power column. Won't work with bottleneck cases of course, for those I believe I'd copy Johnm1's marked-dowel method.