I'm unsure how yours is attached but most were screwed down with the screw hidden under the white diamond. There is a peg(pin) to stop rotation... getting the plastic diamond out will of course be the chore. Prying will likely leave a mark but done carefully with a thin blade and a little(heatgun??) heat may work.. Parts such as this should be available,, check with Brownells as they sell many Remington parts..