This may have been duplicated but very good photos of shot penetration from The Truth About Guns site article by Robert Farago 2-27-2010 "Shotgun Penetration With Various Rounds"
http://thetruthaboutguns.com/2010/02...arious-rounds/
As every test concludes, #4 buckshot is the minimum for self-defense. The Brenneke Slugs are the second best slugs (soon to be third when Buffalo Bore comes out with its 820 grain slug) but the best are the Dixie Slugs and for home defense you could not do better than the Dixie Tri-Ball. It will pattern great out to 40 yards or more - Here is a link to Shotgun World site with photos from the Linebaugh Seminar (May 2007) dated 10-18-07. The Tri-Ball will penetrate two feet plus in wet newspaper and for comparison 00 buckshot will penetrate 7" and #4 will penetrate 3.5" - Here is link to Dixie Slugs
http://dixieslugs.com/ They make an 870 grain hard cast slug "Dangerous Game" but you need a bore that is no less than .730 as the slug will not pass though a choke like the Brennekes. I would probably pick the Tri-Ball as the best all around slug/shot choice if you don't mind the recoil and want the problem done and over quick.