I know this thread is old, but I was thinking about 12 guage slugs and this video crossed my mind:
(Jump to 2:12 to see the effect of a 3 inch magnum slug on a 55 pound block of ballistic media )
http://www.youtube.com/watch?v=5oDG2i6rwjU&list=PL6FB07244EA20A1A9&index=4&feature=plpp_video
(Jump to 2:12 to see the effect of a 3 inch magnum slug on a 55 pound block of ballistic media )
http://www.youtube.com/watch?v=5oDG2i6rwjU&list=PL6FB07244EA20A1A9&index=4&feature=plpp_video