Wilson Case Gage Depth Micrometer Every reloader should know exactly how much your Full Length Sizing Die is pushing back the shoulder. With the NEW Case Gage Depth Micrometer you can do just that! It has never been easier to measure your cases headspace before and after sizing. The Depth Mic allows you to slip the micrometer perfectly over the top of the gage with your case inserted into the gage and take a measurement. Graduations of .001 comes with a Gage Block. One size works for all L.E. Wilson Gages.