A little bit of info.
Last year I ended up finishing off a wounded deer that came up on me, shot him with a 3" #4buck, put a hole in the side of the ribcage you could've set a soda can in to. Short range + large number of pellets = the cookie cutter effect.
While some of the pellets ended up passing completely through, a large number of them did not. This was at a distance of less than 15 feet, and the deer was not particularly large. Penetration seemed a little iffy to me, but that's just one instance. I'll add that the deer died almost instantly, that close range afforded me a very clear heart shot, and most of those pellets found the mark. Definitely effective for close range work in my book, but I'll not be making any 30 yard and beyond shots with it. YMMV.
---Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away.---
---Enlightenment is the ability to take infinite pains---