OK let's start, I already have a 9mm and a .45ACP. Would like to add one more caliber. I want something with stopping power but not a .44 mag. Was thinking of either a .357 magnum or a .40 cal. I would like real world personal feedback. I want something that would be able to penetrate a door or vehicle and still have force to take out the bad guy on the other side. I am going to be travelling quite a lot in my new job and just want something that I can use for personal protection in the event someone in a vehicle causes me to have to defend myself. There have been a number of car jackings in our area as well as shootings on roads so that is why I am wanting something that can penetrate a normal vehicle door/window/windshield and still have some stopping power after that.