Question i have a mossberg 500 12 guage and i just bought a mossberg 24inch rifled slug barrel and i was wondering how many yards is it good for shooting
Answer Depends on the actual type of slugs used.
In general 75 to 125 yards is reasonable.
Here some that are available.
http://www.remington.com/products/ammunition/ballistics/shotshell_slug_loads.asp
http://www.federalpremium.com/products/slug.aspx
http://www.winchester.com/products/catalog/shotshell.aspx