Die Ursache liegt in unterschiedlichen Beschichtungsstärken des Rahmens

you can do this simply by looking down

1x Safety Detent Punger Spring

Optionally

MGL19X-RE (Red)

Glock MOS Adapterplatte - Holosun 407k | 507k NOPAYPAL Die Ursache liegt in unterschiedlichenEEMANN TECH GLOCK MOS adapter plate for HOLOSUN 407K 507K This GLOCK MOS adapter plate from Eemann Tech is made of robust steel and coated in black. This adapter plate is precision engineered and optimally adapted for the Holosun 407K and Holosun 507K models. The MOS set contains all necessary mounting screws for the red dot sight to ensure easy installation on the bolt. However, for mounting on the slide, it is recommended to use the original screws