thanks for the responses, thinking a very low power scope and the federal trueball slugs. not required to shoot a sluggun but just wanting to try it!
If you're gonna scope it, get a barrel with a cantilever scope mount. IME, they stay sighted in much better than the saddle style mounts. Most of those barrels come rifled. I have yet to see a rifled slug barrel not shoot acceptable with Lightfield Hy-Bred 2 3/4" slugs.
http://www.walmart.com/ip/Mossberg-500-Slug-Barrel/4242371
