I recently purchased a RDB. After reviewing comments on several forums, I dedcided to check the screws/bolts/pins for missing/tightness. I found 3 screws/bolts on the Grip Assembly that were loose. But they tightened up. Found 1 that would not. From the Grip Assembly schematic, I have determined that it is a 408 Button Head which screws into the 424 Bolt Stop Weldment on the left-hand side, if the rifle is shouldered by a right-handed shooter. Does not appear to be in danger of falling out or backing out. But it will not tighten. The one on the right-hand side is tight. Have tried to create a ticket on the Kel-Tec website. Will call them on Monday to follow up.