I have screwed a longer screw instead of a smaller screw and it penetrated the plastic backing . I tried unscrewing it but it got stocked. The thing is becoming loose thread. Only way to remove it is taking off the butt sling hole which serves to hold the inside plastic backing. Again it is one of those German engineering that require special tool. I called Walther company and guy told me their tech is off this week and next week. SO much for German engineering I tell you. ANyway , maybe someone can tell me how they unscrew this sling hole?