Since there is no sammi specs on the grooves on 38/357, there are several thickness of moonclips out there. .020, .o22, .025, and then some made for specific headstamp. Winchester is usually the tightest having to use .022 or .020, most others use .o25. Revolver supply has both sizes, and TK custom does also, but will make specific for Starline brass. You want them held secure with just a little movement or will turn in the clip. If they wiggle a lot you will have issues and will have to change something ,brass or moonclips.