I've got a list of firearms that I need in my collection before I just go into "buy cuz it's fun" mode. Three of my needs are a home defense carbine (short and shoulder-fired), I need a second gun that fires .45acp (everyone knows that two is better than one), and I need a second AR-15 (parts interchange is important). Eventually, I'd like to have 3 separate guns to fill all 3 roles, but for now, I am thinking a single AR-15 in 45acp might do the trick. Olympic Arms makes a smokin' 45acp upper with proprietary mags that fit a standard lower. Then I'd build a pretty standard lower from parts. It would cost about $1200 with a good trigger and mid-range red-dot scope. What do y'all think about .45acp carbine vs. .223/5.56 for home defense (not talking 100 yards-plus, I've got a 5.56 20" AR for that).