Sure, slings are available that have a new cap for the end of the shell tube, you just screw it on and the sling attachs to a sling mount on the new end cap. On my 870 the other end of the sling has a strap that attaches to the stock, it is a nylon and velcro rig. I am sure the same is available for the 1300. I bought mine at sporting goods store, but I would think Cabelas would have them.
I would guess that you could also attach the new end cap and have a new sling mount screwed into the stock, but I wouldn't bother.