Numrich has a lot of 18.5 barrels for the 500.
http://www.e-gunparts.com/productschem.asp?chrMasterModel=0840z500
I think what they call the 18.5 "slug" barrel with the beaded sight is probably a cylinder-bore. That would be your cheapest option. If you want rifle sights or ghost ring, it'll cost you more.
http://www.e-gunparts.com/productschem.asp?chrMasterModel=0840z500
I think what they call the 18.5 "slug" barrel with the beaded sight is probably a cylinder-bore. That would be your cheapest option. If you want rifle sights or ghost ring, it'll cost you more.