Part of any good thread is to let people express themselves even when somewhat off topic comments are made by moderators. Part of the discussion sometimes includes little tid bits of off topic information that does seem from time to time bring forth other pertinent content.
I just finished looking for a DVD that was a commercial product that explained home self defense and unfortunately I cannot find it probably because I loaned it to someone and never got it back. Anyway, the guy explained about different calibers and long guns verses pistols, shotguns and the like. In the DVD that I cannot find or I could reference the makers name and you could go out and purchase a copy or I could have made copies and sent them out.
The DVD mentioned calibers, wall penetration and shooting thru your home and killing your sleeping neighbor in the house next to you. Mentioned in the DVD was that a gun that was long AKA Shotgun, rifle and so forth could easily be rendered useless in your hands if the intruder go close enough to grab it. Rifles and shotguns were a No No in the DVD as were high powered short barrel rifles and or something with a light, strobe, and laser on them simply because that point of light shows the intruder exactly where you are and where to shoot in order to take you out.
The DVD mentioned a pistol with a slower velocity bullet with a larger mass. Why? Probably the ability to knock down and keep the intruder down. Its hard to explain to law inforcement why exactly you spent 15 rounds into the intruder in order to stop them and a lot easier to explain 3 or 4 rounds.
While I cannot prove the existance of the DVD I had so it probably doesn't exist to some so I will recommend that you look into some of the free DVD's out there on protecting yourself in the home.
The above mentioned material is why I will back myself with a 1911 any day as opposed to an AR15 with a light or a tactical shotgun.