Being a proficient handgun shooter with many years of use, on the job and off, I can wholeheartedly recommend a short barreled 12 bore only. Handguns take much practise to become proficient in their use, and easily miss at very close range by someone who is quite excited. Just a few hours of GOOD practise can develope all the skill necessary to use a shotgun properly. You, the home defender, must be the only one giving evidence at the trial. With a single bullet fired from a handgun, this is less likely.
: For inside jobs, I'd recommend #1,2,3 or 4 buck and an open choke. The smaller buck-shot, the better as it will be equally or more effective at such close range as 00 buck due to multiple hits and be less likely to hurt someone else in adjacent rooms due to less penetrative force.
: A shotgun is much easier to control and has a much more dramatic 'Visual' effect which is liely to difuse the situation until help arrives via 911.
: For those who insist on using a handgun, there are few better or even the equal of the model 1911 loaded with Speer Flying ashtrays.(200gr.hp's)(or more modern rapid expanding projectile. The trouble is that few will retire to the needed practise, vitally necessary to become proficient with it. I do not consider anything smaller than .41 cal. to be good enough for those who can legally use a firearm for self defense. The only .38 I would consider is a .38/40, which is actually a .408". The .35's don't muster.