Re: Primer issues with Dillon 550B
The primer feed tube has a plastic end that holds the primers for the bar to pick up. There is also a little spring loaded white plastic rod that sits under the installed primer tube in the primer system body, stopping the primers from falling out of the tube when the primer tube is installed in the primer system body. The little spring loaded white plastic rod holds the primers until the cup on the bar pushes the little spring loaded white plastic rod out of the way and a primer falls into the bar's primer cup. You have to be using the correct tube (there is one for the large primers and one for the small primers). And the tube's plastic end is indexed to fit in the primer system body. The tube must seat all the way down until the plastic end on the primer tube almost touches the little spring loaded white plastic rod. You must use the weighted plastic stick in the primer tube to assure the primers move down by gravity.
When setting up the primer bar you have to shine a light onto the primer cup on the primer bar when it is under the tube all the way and look down the tube from the top and see that the cup of the primer bar is in perfect alignment with the plastic tip of the primer tube. The allen screw and nut are the way you adjust that end of the primer bar travel to get this perfect alignment.
Have you read the instruction manual? All of the adjustments, I believe, are covered there (??).