Holy ****... where to start.
First of all, having two blanks, rock salt, etc in your home defense weapons is IDIOTIC. Only slightly less idiotic is the "shoot to maim" idea that has been presented.
Get one thing straight people, if you shoot someone you are going to jail. Period. The thing that will alter the length of your stay in the slammer is whether the shoot was justified.
I know most of you wont care, but here's the the GoldenRule: You can only shoot if you, or your loved one, is under threat of great bodily harm or death. If some punk is running out your front door with your 5K stereo system, or some other punk is stealing your X, and you shoot them, you'll easily be convicted of murder. Your life is essentially over.
If you are under attack and fear for your life, then you do not shoot to "hurt" or "maim". You also do not shoot to kill. You shoot to stop. To stop the threat that is about to kill you (or so you better think). Dead men tell no tales, and hire no attorneys to sue the **** out of you for blowing their foot off.
Generally handgun ammo will over penetrate the most in an indoor setting. Buckshot also penetrates most walls thru and thru. Birdshot is marginally less susceptable to over penetration. I know it sounds weird, but some of the least penetrative rounds (once the hit something @ 3000+fps) are in .223 caliber (AR-15/M-16 type rifles). Yes, there are franglibles out there like the glaser, and they are a bargain at only $2/round.
Sorry for the fatherly like lecture, but these are things you should DEFINITELY know if you are planning on investing in a weapon. You have a bad shoot and you'll regret it for the rest of your life.