I want to use my standard 870 express as an HD shotty when I need to. Anybody know where the cheapest place to find an 18.5 in barrel for a remington 870? I know Cabelas has an 18 inch for $120, but doesn't the 18in fall 1/2in short of matching up with a magazine extension? I don't know much about shotties, but I was told 18.5 in is better than the 18 in. Any help would be great.