Have you guys checked out the tannerite and other exploding targets? they are totally legal (for now at least) and a blast!!!!!
Check out what 2 tubs (2.5 lbs each) do to an old fridge in the Utah desert. This was Star Targets brand. (available from cabelas, impact guns, sportsmans guide) I'm embarrassed that it took 3 shots to hit it at 200 yards. I think my 270 got a bunch of gifts thrown on it in the back of our suburban, hence the first shot off 3 feet at that distance
http://www.youtube.com/watch?v=07e6KrVHhDg