Tam has a pretty good post on the subject. I have both a 20″ and carbine length AR. I shoot the 20″ more often because that’s what I compete with when I shoot CMP/high-power. I’ve shot a few practical matches with my carbine, but I would consider it my go-to gun in a home defense situation if I kept it at the ready. It’s the keeping it at the ready part I’ve never been able to bother with.
Maybe I’m just not all that committed to home defense, but it’s always been easier or me to rely on a pistol for those purposes. I have to remember to lug a carbine back down to the safe if I’m leaving home for any period of time, then to get it back out again when I return. While, I have home-defense-appropriate fragmenting ammunition for the rifle, unless it’s a seriously messed up situation where I have time to go downstairs and unlock the safe, I’m probably going to be using my Glock.
I’ve always considered a rifle or shotgun to be a pain in the butt to deal with for home defense. What solutions do you guys use that would that would allow it to be used for home-defense, but avoid the scenario where someone breaks into the house and steals it, or worse, uses it against the returning homeowners?