For all of my presses, I have converted to O rings to replace the spring clips, so that the shell holders can float a little. I have also modified my press technique so that the shell holder/case has a chance to center itself on the die. For may PPC work I have a shell holder that is the "wrong" size, that fits looser than the correct one, and it has had its lower flange and the part that is smaller in diameter above it reduced slightly in their diameters by a friend who has a lathe. The O ring that I use is packaged 10 each by Danco. the product number is 96754, and the size is 3/4" OD x 5/8" ID x 1/16. For tight spring clips, I roll my shell holders counterclockwise as I am inserting them.