Remingtons still sells their folding metal stocks; except only to LEO. If you've got a cop buddy who'd help you out, that's your ticket.
BTW, I took the Rem. folder off mine. Hated the way the pistol grip pounded the daylights out of the web of my hand (so I'm a wimp) when I shot slugs. I also disliked the cold metal against the cheek and the third dislike was the square metal buttplate. God does it hurt (so I'm a wimp again) when I shouldered it for slugs. Since then, the stock has been replaced with a Speedfeed that carries four extra shells. I can shoot slugs all day and go home without having to soak in the tub.