Well...you have a few options. If you have the money to sink into a slug barrel, B Square mount, and a scope...then I say shoot slugs until your shoulder turns purple. If you don't have the money to do that I would suggest that you shoot buckshot. I have killed many deer with buckshot over the years and I haven't ever considered it too damaging to the meat. If you have a screw in choke system then I would recommend that you go out and get one of those extended extra full chokes or compensators and use buckshot. 40 yards and in is prime buckshot territory!