First, I'll state that there is NO problem with the Lee equipment. I spent a bit of time last night setting up my Loadmaster to load 5.56 NATO. Lee lists the 4S for 223, so I used that. My problem is my Lake City 5.56 brass will not go. I can force it, but that just causes other problems, and takes lots of time. I switched it out for the 19S (9MM). It works, but is a little loose. Cases are not aligning 100% of the time with the dies.
The lake City brass seems to have a slightly larger diameter rim, or thicker rim. Probably flattened a bit from firing. Could also be rim is a little 'wavy' from the extractor pull.
What I need is an idea to open up the shell plate slots to reliably accept the cases. Anybody have this problem and a fix?