Parabellum - Don't know if you caught these threads when I posted them, but they might give an idea of the relative power of the 12 gauge vs. the .223rem cartridge.
12 guage :
http://www.thefiringline.com/forums/...d.php?t=175590
http://www.thefiringline.com/forums/...d.php?t=155650
.223 remington :
http://www.thefiringline.com/forums/...d.php?t=175604
http://www.thefiringline.com/forums/...d.php?t=173924
WRT the guns, I really would not worry about the home invasion/hostage taking situation. I think that the person who would utilize this tactic might reasonably be lumped into the 'dedicated fighter' category - those who will not reason and can only be stopped. Like a member of Team Jihad or a severely intoxicated person. The likelihood of running into one like that and them having the presence of mind during the situation (because most criminals are under stress too) to take a hostage seems somewhat, low-percentage. Anyhow, I like the round that splits the blocks into three pieces for those special cases...
Tom