Wow this was a great thread, glad I hopped on to do some reading.
I never saw a huge advantage of buying a really high quality shotgun (those ones costing over a grand), a shotgun does some serious damage at close range, doesn't seem to matter about quality. But, if you get a really cheap one, it may not be reliable, and since you are looking at home defense, you need that more than anything (why many people use revolvers for home defense, not much can go wrong with them). The models in this thread are good choices.
My dad had a shotgun in the house when I grew up, for some reason, that was something he told us NOT TO TOUCH, and we never touched it, and mind you, it wasn't locked up. He didn't keep shells in it, and even knowing that, we never touched it.
As I got older, I realized that it seemed silly to not keep the shells near the gun, or IN the gun, and I asked him why, and he said he worried about one of us touching it and having an accident. So, this while keeping us safe, would be useless if someone was in the home trying to harm us. Unless he had time to get to the shells, fumble around with them, load the gun, pump, shoot, etc.
So then you are left with a handgun as an option. I have a pistol still, I used to have two when I shot a lot with my dad. I kept one just to keep in the house, and to go shooting every now and again. Handguns are easier to hide if you have kids in the house, and you can even go as far as to keep the magazine full of rounds, but don't chamber it, so there's one more element of safety for a child that could get his hands on it (tough to figure out, tough to chamber a round).
There are handgun bullets that are mini-shotgun shells. They don't penetrate as deeply and are good for that close-up kind of defense shooting, you don't have to worry about blowing a hole through the wall and hitting someone two rooms down the hall.
Quick Google search -
http://www.cheaperthandirt.com/64455-5.html. They aren't as great as a hollowpoint for a total stop, but do scatter to help you hit your target.
Like others have said, absolutely practice with whatever you choose to go with. Being in a bad situation is a lot different than plinking at cans out in a field.
And also as noted through the thread, the law seems to help protect criminals anymore. I've heard that not keeping your gun locked in a safe will be touted as "Aggressive" or "Gun Nut" in a court, almost like you were waiting to take a shot on someone's life. I'm not sure if there's any truth to it, I never looked into it, but I could see something like that being done in an attempt to make someone else seem innocent. But then again, it's your home, you can defend it within reason. Killing someone that is about to run out the door isn't within reason obviously, your life isn't in immediate danger.
There's something really intimidating about hearing a shotgun being loaded, so I vote shotgun and keeping it up high away from the kids. Stress to stay away, etc. I also vote to get a dog if you don't have one, they are great alarm companies and can buy you time.
Also of note - i don't have kids in my house, so am just relaying an opinion.
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