Yes the slug barrel has a cantilevered mount that extends over the receiver the advantage of the cantilevered mount is that the scope holds zero when the barrel is removed and replaced as it is zeroed to the barrel and stays attached to the barrel when it is removed If You want to use a scope with the 28 inch rem choke this is also easily done using a Saddle mount for the Remington 870 (purchased separately from aftermarket sources)

William, yes Sir. The perfect scope for the he cantilevered 23" rifled barrel's Integral Rail is the (Nikon Prostaff P3 3-9x40 Shotgun Scope BDC 200 Reticle) : budsgunshop.com/catalog/product_info.php/products_id/712016327/nik+3-9x40+prostaff+p3+shotgun+hunter+bdc+200

Yes indeed, the cantilevered 23" rifled barrel has an integral rail attached, on which you can readily mount a scope (with the appropriate rings) or a red dot.