Why size a case down so much you have to open the neck back up? The 44 sizer dies I've measured were ~ .448". I bought a Lee 44 Carbide Sizing Die and using 325 mesh Diamond Powder I opened it up to .450. I coated 1/2 inch Dremel felt wheels with spray adhesive and rolled them in Diamond Powder and let them dry. Soaking them a little in soapy water before you polish seems to work better. Using a Makita Drill on high I gained a little over .0001 each try and the wheels needed to be changed after 1 or 2 minutes. Once they dry out the wheels can be recoated. Arrowhead Lapidary Supply sells small quantities of Abrasives. The wheel in front is a new one coated with diamond. The one behind has been used. Don't know why it turns black.