Rifled slug barrel is more accurate than smooth - but it has to be legal in that state.. check your regulations.
If using a smooth bore barrel make sure you have a open choke in when shooting slugs... Cylinder or IC are ok.. NOT full chokes.
When you get your barrel try a half dozen slug types - and make sure you try the more common plane Jain variants. I have a very expensive slug barrel (SBE with a Slug barrel) and it shoots plain old Winchester 1oz slugs the best... plus they are cheap so I get to practice a bit with them each year.
