MAS, Thanks for sharing your knowledge with us. I live in a neighborhood with neighbors houses ten feet away on the left and right of me and houses across the street and behind me. I have an S&W MP15X and a bullpup FS2000. I've been looking for a .223 round for home defense. Being surrounded by homes in the way that I am I don't really have a angle or shot that I could take without being worried about over penetration or missed shots. All the good and recommended ammo is designed FOR barrier penetration. After spending some time searching and researching I found the Hornady 40gr tap urban. http://www.hornadyle.com/products/more_detail7d24.html?id=130&sID=73&pID=1 It seems designed for a home defense situation like mine where over penetration and barrier penetration is bad news waiting to happen . The trade off is poor penetration when striking the intended target. Would this ammo be good in my situation? Due to the poor penetration performance of the ammo could I just keep shooting the bad guy until he is stopped? I think 3 to 5 of these on target could be effective? The next tap up in size, 55gr, states that it will begin to fragment in barriers but will still retain sufficient velocity weight and penetration to provide significant stopping power upon exit from barrier..... which is something that I don't want. All that separates my dining room and family room from my neighbors houses is my windows, ten feet, and his windows. Could four or five of these rounds in a bad guy potentially stop him? I want to defend my home and family against harm from bad guys but I also feel a responsibility to try and protect my neighbors lives by the round i choose as much as possible in the event one of my bullets crosses into their home. Any advice on what round I should use to try and accomplish that?