a 12 gauge with number 4 or number 6 shot is a pretty good compromise. Buckshot will go through walls easily. So will most any pistol round and certainly any rifle. So you're firing a gun inside your house, That's obviously a desperate situation. You are compelled to not fire in the direction you think other occupants are located. Even if you've never lived through it, you know that you don't have a lot of time to contemplate before making your decision. if the bad guy is 10 feet away from you or less, which is most commonly the case, number four or number six will turn him into Swiss cheese. and particularly after hitting a bad guy the pellets, if they do pass through him, are not likely to have that much velocity left. I have personally seen buckshot pass all the way through a deer.. So that's that.