Rear sight very loose - LPA Adjustable Red Front Green Rear Kimber Fiber Optic Sight Set

The sight appears fine but when I came to fit it, I had some issues. The front blade went in fine with a sight pusher tool. The rear sight is so loose that if you tip the slide more than 45 degrees from the horizontal, it just falls out. Yes, there are two very small set screws, but I don’t see them holding long against prolonged 45 ACP firing. I ended up using a punch to dimple the rear sight to deform the metal and mike it more of a snug fit. That was only moderately successful. Not recommended.