Nice looking but doesn't fit anything - Guntec USA Gen 3 AR-15 Ejection Port Dust Cover Assembly

I've tried this on multiple upper receivers including Aero Precision (mil-spec and M4E1), Anderson, WMD, store-brand generics, anodized, Cerakoted, and raw, and it doesn't fit any of them. The radius on the the upper ends is the same as on a mil-spec door, but the mil-spec door is a flimsy piece of sheet steel. The radius is simply too sharp for the thicker billet aluminum to fit into the recess on the side of any upper receiver. The Timber Creek billet ejection port door has a larger radius, so it fits, but it's about 50/50 on actually latching and even less on staying latched, so I can't win with a billet door....