Well respected Massad Ayoob recommends 20ga.
http://www.backwoodshome.com/articles2/ayoob120.html
You can buy a $300 870 from walmart then cut the 21" barrel to 18" and replace the stock with a birdshead grip for a very comfortable shooting and easy to handle shotgun.
http://www.backwoodshome.com/articles2/ayoob120.html
You can buy a $300 870 from walmart then cut the 21" barrel to 18" and replace the stock with a birdshead grip for a very comfortable shooting and easy to handle shotgun.