Are you saying it acts like a 'U' die and sizes the 'bulge' area? I know some guys used to run a std. or 'U' die at #1 position (progressive) and an FCD at the crimp station, but never heard of it reducing the 'bulge' area. So when stuff gets 'squished', something has to go somewhere.If you use a Lee Factory Crimp die it will cycle through your reloader and your gun. Make sure your ducks are in a row before using a Lee Factory Crimp die because it will squish everything to where it should be and that's not always a good idea.