I don't have one, but I've done some research on it, barrels can be bought from H&R if they have any, toll free (866)776-9292, which they haven't for quite a while, but that can always change, they don't make a 20ga slug barrel or gun that I could find, just 12ga. The PP is an 870 clone, some 870 parts and accessories will fit, unfortunately, barrels don't, but you can buy the barrels OTC if you can find them. H&R was out of scope rails for it for a long time also.
Tim