[Samm]

Got a useful response on another forum. The front screw doesn’t actually secure the rail, it’s meant for attaching a mirage shield. Therefore, if you overtighten the front screw it’ll apply upward pressure and lift the rail.

For the time being, I’ve removed the screw and clamped the rail down. Doubtful it’ll return to position though and I’ll probably end up buying a replacement rail.