I have a 12ga Mossberg 500 Persuader model. It has a capacity of 8 rounds in a magazine tube that is flush with the 20 1/2 inch cylinder bore barrel. It makes a great bedroom gun but that's about it. I really want to pick up a longer barrel with interchangable choke tubes for shooting clays and some hunting. However because I have the longer magazine tube I assume I'll need a shorter one to work with the new barrel but what else do I need? Also I would like to use the gun to shoot rifled slugs, what choke tube should I use or would it work just as well to use the short barrel since it has no choke? Any advice will be greatly appreciated.