These cases are specially modified to work with Lock-N-Load Precision gauges. A special fine thread is used to attach them to the gauges, ensuring that they remain perfectly square for precise alignment in the chamber of your firearm. Second, the neck of the case is made perfectly round and opened slightly to allow a standard diameter bullet to slip into the case mouth effortlessly, but concentrically, to ensure the most precise results possible.If your case is not listed below and you are needing a case modified, please follow the instructions listed below.Please include contact information, two fired pieces of brass not deprimed or resized (in case there are issues creating the modified case) as well as a check for $15.00. Please make checks payable to Hornady Manufacturing. We ask that you please use FedEx, UPS, or other direct shipping service. Using USPS may result in item returned to sender.