Well said

but I'd suggest buying a 9mm semi auto pistol. shotgun may be unwield for indoor use because it is bit too long. of course if you can get the saw-off shotgun (short barrel and pistol-grip-like stock) it will be good but be aware in most states the saw-off is illegal. also if you fire a shotgun in your home, the damage to the house will be extensive. pistol bullet holes are easier to fix.

aiming is not a problem, since vast majority of gun fight occurs within 5m and finishes within 3 shots.

Don't buy a revolver. it is slow to load.