Blurry and dark and hard to see what you are talking about. ...it looks like a single socket for a QD sling swivel? is the plate magpul? Or the sling swivel magpul? Does the socket extend forward above the plate? It may not be deep enough to lock the button in. Some lowers have a deep relief at that spot and some dont. Explain why it doesnt fit. Clearance issue? Wont stay locked it? Doesnt fit at all? help us help you man.