Mostly happy - SIG SAUER P365 Sub-Compact 9mm Luger 12 Round Pistol Magazine

The magazine works as expected, until you place the spacer and new end cap on it. Then it only holds 11 rounds. I mainly bought it because I’ve got large hands, and wanted the extra support for my little finger, so that part is fine. But once it’s set up, the 12th rounds round won’t fit